Derivation method and apparatuses with candidate motion vectors

ABSTRACT

A moving picture coding apparatus for coding a current block is provided. A first candidate is derived from a first motion vector that has been used to code a first block, and it is determined whether a total number of candidates including the first candidate is less than a maximum candidate number. A second candidate having a second motion vector is derived when the total number of the candidates is less than the maximum candidate number, with the second motion vector including a zero vector. A candidate is selected from a plurality of candidates including the first candidate and the second candidate, and the current block is decoded using the selected candidate.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 17/337,094,filed Jun. 2, 2021, which is a continuation of U.S. patent applicationSer. No. 16/217,590, filed Dec. 12, 2018 and now U.S. Pat. No.11,057,639, which is a continuation of U.S. patent application Ser. No.15/729,006, filed Oct. 10, 2017 and now U.S. Pat. No. 10,645,413, whichis a continuation of U.S. patent application Ser. No. 15/140,921, filedApr. 28, 2016 and now U.S. Pat. No. 9,819,961, which is a continuationof U.S. patent application Ser. No. 14/612,728, filed Feb. 3, 2015 andnow U.S. Pat. No. 9,609,356, which is a continuation of U.S. patentapplication Ser. No. 13/482,549, filed May 29, 2012 and now U.S. Pat.No. 8,989,271, which claims the benefit of U.S. Prov. Pat. Appl. No.61/491,381, filed May 31, 2011. The entire disclosure of each of theabove-identified documents, including the specification, drawings andclaims, is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a moving picture coding method and amoving picture decoding method.

BACKGROUND ART

In moving picture coding processing, in general, the amount ofinformation is reduced by utilizing redundancy in the spatial directionand the temporal direction which moving pictures have. Here, in general,transform to a frequency domain is used as a method utilizing redundancyin the spatial direction. Further, inter-picture prediction(hereinafter, referred to as “inter prediction”) coding processing isused as a method utilizing redundancy in the temporal direction. Ininter prediction coding processing, when a picture is coded, a codedpicture that appears before or after a current picture to be coded inthe display time order is used as a reference picture. A motion vectoris derived by performing motion detection on the current picturerelative to the reference picture. Then, redundancy in the temporaldirection is eliminated by calculating a difference between image dataof the current picture and predicted image data obtained by performingmotion compensation based on the derived motion vector (for example, seeNon Patent Literature (NPL) 1).

Here, in motion detection, a difference value between a current block ina current picture to be coded and a block in a reference picture iscalculated, and a block in the reference picture with which the smallestdifference value is obtained is determined as a reference block. Then, amotion vector is detected using the current block and the referenceblock.

CITATION LIST Non Patent Literature

-   [NPL 1] ITU-T Recommendation H.264, “Advanced video coding for    generic audiovisual services”, March, 2010-   [NPL 2] JCT-VC, “WD3: Working Draft 3 of High-Efficiency Video    Coding”, JCTVC-E603, March 2011

SUMMARY OF INVENTION Technical Problem

However, there is a demand for the above conventional technique toachieve an improvement in coding efficiency, in coding and decoding amoving picture using inter prediction. In view of this, an object of thepresent invention is to provide a moving picture coding method and amoving picture decoding method which improves coding efficiency, incoding and decoding a moving picture using inter prediction.

Solution to Problem

A moving picture coding method according to an aspect of the presentinvention is a moving picture coding method for calculating a motionvector predictor to be used when coding a motion vector of a currentblock to be coded, and coding the current block, to generate abitstream, the method including: deriving each of one or more firstmotion vector predictor candidates, based on a motion vector used forcoding a block spatially or temporally adjacent to the current block;deriving one or more second motion vector predictor candidates eachhaving a predetermined vector as a motion vector; selecting, from amongthe one or more first motion vector predictor candidates and the one ormore second motion vector predictor candidates, the motion vectorpredictor to be used for coding the motion vector of the current block;and adding an index for identifying the motion vector predictor to thebitstream.

It should be noted that these general and specific aspects may beimplemented using a system, a method, an integrated circuit, a computerprogram, a computer-readable recording medium such as a compact discread only memory (CD-ROM), or any combination of systems, methods,integrated circuits, computer programs or recording media.

Advantageous Effects of Invention

According to an aspect of the present invention, it is possible toimprove coding efficiency, in coding and decoding a moving picture usinginter prediction.

BRIEF DESCRIPTION OF DRAWINGS

These and other objects, advantages and features of the invention willbecome apparent from the following description thereof taken inconjunction with the accompanying drawings that illustrate a specificembodiment of the present invention. In the Drawings:

FIG. 1A is a diagram for describing an example of a reference picturelist for a B-picture;

FIG. 1B shows an example of a reference picture list for a predictiondirection 0 for a B-picture;

FIG. 1C shows an example of a reference picture list for a predictiondirection 1 for a B-picture;

FIG. 2 is a diagram for describing motion vectors in a temporal motionvector prediction mode;

FIG. 3 shows examples of motion vectors of adjacent blocks used in amotion vector predictor designating mode;

FIG. 4 is a diagram for describing in (a) and (b) an example of a motionvector predictor candidate list for the prediction direction 0;

FIG. 5 is a diagram for describing in (a) and (b) an example of a motionvector predictor candidate list for the prediction direction 1;

FIG. 6 shows examples of assignment of bit strings to motion vectorpredictor indices;

FIG. 7 is a flowchart showing an example of coding processing performedwhen the motion vector predictor designating mode is used;

FIG. 8A shows an example of calculation of a motion vector predictor;

FIG. 8B shows an example of calculation of a motion vector predictor;

FIG. 9 is a block diagram showing an example of a configuration of amoving picture coding apparatus which codes a moving picture using themotion vector predictor designating mode;

FIG. 10 is a flowchart showing an example of decoding processingperformed when the motion vector predictor designating mode is used;

FIG. 11 is a block diagram showing an example of a configuration of amoving picture decoding apparatus which decodes a moving picture codedusing the motion vector predictor designating mode;

FIG. 12 shows syntax used when a motion vector predictor index is addedto a bitstream;

FIG. 13 is a block diagram showing a configuration of a moving picturecoding apparatus according to Embodiment 1;

FIG. 14 is a flowchart showing processing operation of the movingpicture coding apparatus according to Embodiment 1;

FIG. 15 shows an example in (a) and (b) of a motion vector predictorcandidate list for the prediction direction 0 in Embodiment 1;

FIG. 16 shows an example in (a) and (b) of a motion vector predictorcandidate list for the prediction direction 1 in Embodiment 1;

FIG. 17 is a flowchart showing processing for calculating a motionvector predictor candidate and a motion vector predictor candidate listsize in Embodiment 1;

FIG. 18 is a flowchart showing processing for determining whether acandidate is an available predictor candidate in Embodiment 1;

FIG. 19 is a flowchart showing processing for adding a zero candidate inEmbodiment 1;

FIG. 20 is a flowchart showing processing regarding selection of amotion vector predictor candidate in Embodiment 1;

FIG. 21 is a diagram for describing in (a) and (b) an example of amotion vector predictor candidate list for the prediction direction 0;

FIG. 22 is a block diagram showing a configuration of a moving picturecoding apparatus according to Embodiment 2;

FIG. 23 is a flowchart showing processing operation of the movingpicture coding apparatus according to Embodiment 2;

FIG. 24 is a block diagram showing a configuration of a moving picturedecoding apparatus according to Embodiment 3;

FIG. 25 is a flowchart showing processing operation of the movingpicture decoding apparatus according to Embodiment 3;

FIG. 26 is a block diagram showing a configuration of a moving picturedecoding apparatus according to Embodiment 4;

FIG. 27 is a flowchart showing processing operation of the movingpicture decoding apparatus according to Embodiment 4;

FIG. 28 is a block diagram showing a configuration of a moving picturecoding apparatus according to Embodiment 5;

FIG. 29 is a flowchart showing processing operation of the movingpicture coding apparatus according to Embodiment 5;

FIG. 30 shows an example in (a) and (b) of a motion vector predictorcandidate list for the prediction direction 0 in Embodiment 5;

FIG. 31 shows an example in (a) and (b) of a motion vector predictorcandidate list for the prediction direction 1 in Embodiment 5;

FIG. 32 is a flowchart showing processing for calculating a motionvector predictor candidate and a motion vector predictor candidate listsize in Embodiment 5;

FIG. 33 is a flowchart showing processing for updating the number ofavailable predictor candidates in Embodiment 5;

FIG. 34 is a flowchart showing processing for adding a new candidate inEmbodiment 5;

FIG. 35 is a flowchart showing processing regarding selection of amotion vector predictor candidate in Embodiment 5;

FIG. 36 is a block diagram showing a configuration of a moving picturecoding apparatus according to Embodiment 6;

FIG. 37 is a flowchart showing processing operation of the movingpicture coding apparatus according to Embodiment 6;

FIG. 38 is a block diagram showing a configuration of a moving picturedecoding apparatus according to Embodiment 7;

FIG. 39 is a flowchart showing processing operation of the movingpicture decoding apparatus according to Embodiment 7;

FIG. 40 is a flowchart showing processing for calculating the number ofavailable predictor candidates in Embodiment 7;

FIG. 41 is a flowchart showing processing for calculating a motionvector predictor candidate in Embodiment 7;

FIG. 42 shows an example of syntax used when a motion vector predictorindex is added to a bitstream;

FIG. 43 shows an example of syntax used when a motion vector predictorcandidate list size is fixed to the maximum value of the number ofmotion vector predictor candidates;

FIG. 44 is a block diagram showing a configuration of a moving picturedecoding apparatus according to Embodiment 8;

FIG. 45 is a flowchart showing processing operation of the movingpicture decoding apparatus according to Embodiment 8;

FIG. 46 shows an overall configuration of a content providing system forimplementing content distribution services;

FIG. 47 shows an overall configuration of a digital broadcasting system;

FIG. 48 shows a block diagram illustrating an example of a configurationof a television;

FIG. 49 shows a block diagram illustrating an example of a configurationof an information reproducing/recording unit that reads and writesinformation from and on a recording medium that is an optical disk;

FIG. 50 shows an example of a configuration of a recording medium thatis an optical disk;

FIG. 51A shows an example of a cellular phone;

FIG. 51B is a block diagram showing an example of a configuration of acellular phone;

FIG. 52 illustrates a structure of multiplexed data;

FIG. 53 schematically shows how each stream is multiplexed inmultiplexed data;

FIG. 54 shows how a video stream is stored in a stream of PES packets inmore detail;

FIG. 55 shows a structure of TS packets and source packets in themultiplexed data;

FIG. 56 shows a data structure of a PMT;

FIG. 57 shows an internal structure of multiplexed data information;

FIG. 58 shows an internal structure of stream attribute information;

FIG. 59 shows steps for identifying video data;

FIG. 60 shows an example of a configuration of an integrated circuit forimplementing the moving picture coding method and the moving picturedecoding method according to each of embodiments;

FIG. 61 shows a configuration for switching between driving frequencies;

FIG. 62 shows steps for identifying video data and switching betweendriving frequencies;

FIG. 63 shows an example of a look-up table in which video datastandards are associated with driving frequencies;

FIG. 64A is a diagram showing an example of a configuration for sharinga module of a signal processing unit; and

FIG. 64B is a diagram showing another example of a configuration forsharing a module of the signal processing unit.

DESCRIPTION OF EMBODIMENTS (Underlying Knowledge Forming Basis of thePresent Invention)

In the moving picture coding scheme referred to as H.264 which hasalready been standardized, three picture types, namely, I-picture,P-picture, and B-picture are used to compress the amount of information.

An I-picture is not coded by inter prediction coding processing.Specifically, an I-picture is coded by intra-picture prediction(hereinafter, referred to as intra prediction) coding processing. AP-picture is coded by inter prediction coding by referring to onealready coded picture that appears before or after a current picture tobe coded in the display time order. A B-picture is coded by interprediction coding by referring to two already coded pictures that appearbefore or after the current picture in the display time order.

In inter prediction coding, a reference picture list for identifying areference picture is generated. A reference list is a list in whichreference picture indices are assigned to coded reference pictures to bereferred to in inter prediction. For example, since B-pictures can becoded by referring to two pictures, two reference lists (L0, L1) aregenerated.

FIG. 1A is a diagram for describing an example of a reference picturelist for a B-picture. FIG. 1B shows an example of a reference picturelist 0 (L0) for the prediction direction 0 in bidirectional prediction.Here, in the reference picture list 0, value 0 of the reference pictureindex 0 is assigned to reference picture 0 at display order 2. Further,value 1 of the reference picture index 0 is assigned to referencepicture 1 at display order 1. Further, value 2 of the reference pictureindex 0 is assigned to reference picture 2 at display order 0.Specifically, reference picture indices having smaller values areassigned to reference pictures in order of temporal proximity to acurrent picture to be coded in display order.

FIG. 1C shows an example of the reference picture list 1 (L1) for theprediction direction 1 in bidirectional prediction. Here, in thereference picture list 1, value 0 of the reference picture index 1 isassigned to reference picture 1 at display order 1. Further, value 1 ofthe reference picture index 1 is assigned to reference picture 0 atdisplay order 2. Further, value 2 of the reference picture index 2 isassigned to reference picture 2 at display order 0.

In this manner, it is possible to assign reference picture indiceshaving different values for the prediction directions to a referencepicture (reference pictures 0 and 1 in FIG. 1A), and reference pictureindices having the same value for the prediction directions to areference picture (reference picture 2 in FIG. 1A).

Further, in the moving picture coding scheme referred to as H.264 (NPL1), a motion vector detection mode is used as an inter prediction codingmode for blocks to be coded in a B-picture. In the motion vectordetection mode, a difference value between predicted image data andimage data of a current block to be coded, and a motion vector used forgenerating the predicted image data are coded. Further, in the motionvector detection mode, it is possible to select bidirectional predictionor unidirectional prediction, as the prediction direction. Inbidirectional prediction, a predicted image is generated by referring totwo already coded pictures which appear before or after a currentpicture to be coded. In unidirectional prediction, a predicted image isgenerated by referring to one already coded picture which appears beforeor after a current picture to be coded.

Further, in the moving picture coding scheme referred to as H.264, acoding mode referred to as a temporal motion vector prediction mode canbe selected when a motion vector is derived in coding a B-picture. Aninter prediction coding method in the temporal motion vector predictionmode is described using FIG. 2 .

FIG. 2 is a diagram for describing motion vectors in the temporal motionvector prediction mode. Specifically, FIG. 2 shows the case where blocka in picture B2 is to be coded in the temporal motion vector predictionmode.

Here, motion vector vb is utilized which is used when block b(hereinafter, referred to as “co-located block”) at the same position inpicture P3 as that of block a is coded, picture P3 being a referencepicture which appears after picture B2. Motion vector vb is a motionvector used when block b is coded by referring to picture P1.

Two reference blocks for block a are obtained from picture P1 which is aforward reference picture and picture P3 which is a backward referencepicture, using motion vectors parallel to motion vector vb. Then, blocka is coded by performing bidirectional prediction based on the twoobtained reference blocks. Specifically, motion vectors used when blocka is coded are motion vector va1 with respect to picture P1 and motionvector va2 with respect to picture P3.

In addition, a motion vector predictor designating mode is considered tobe used (NPL 2) as a method for coding motion vectors of blocks to becoded in a B-picture or a P-picture. In the motion vector predictordesignating mode, motion vector predictor candidates are generated basedon motion vectors used when coding blocks adjacent to a current block tobe coded. Then, a motion vector predictor is selected from among themotion vector predictor candidates, and a motion vector of the currentblock is coded. At this time, an index of the selected motion vectorpredictor and the like are added to a bitstream. Consequently, the samemotion vector predictor as the motion vector predictor used for codingcan be selected also when decoding is performed. A specific example isdescribed with reference to FIG. 3 .

FIG. 3 shows examples of motion vectors of adjacent blocks which areused in the motion vector predictor designating mode. In FIG. 3 ,adjacent block A is a coded block adjacent to and located at the left ofa current block to be coded. Adjacent block B is a coded block adjacentto and located on the current block. Adjacent block C is a coded blockadjacent to and located at the upper right of the current block.Adjacent block D is a coded block adjacent to and located at the bottomleft of the current block.

In FIG. 3 , the current block is a block which is coded by bidirectionalprediction, and has, as a result of motion detection or the like, motionvector MvL0 in the prediction direction 0 as a motion vector relative toa reference picture indicated by reference picture index RefL0 for theprediction direction 0, and motion vector MvL1 in the predictiondirection 1 as a motion vector relative to a reference picture indicatedby reference picture index RefL1 for the prediction direction 1. Here,MvL0 is a motion vector for which a reference picture identified usingthe reference picture list 0 (L0) is referred to. Further, MvL1 is amotion vector for which a reference picture identified using thereference picture list 1 (L1) is referred to.

Adjacent block A is a block coded by unidirectional prediction in theprediction direction 0. Adjacent block A has motion vector MvL0_A in theprediction direction 0 as a motion vector relative to a referencepicture indicated by reference picture index RefL0_A for the predictiondirection 0. Further, adjacent block B is a block coded byunidirectional prediction in the prediction direction 1. Adjacent blockB has motion vector MvL1_B in the prediction direction 1 as a motionvector relative to a reference picture indicated by reference pictureindex RefL1_B for the prediction direction 1. Adjacent block C is ablock coded by intra prediction. Further, adjacent block D is a blockcoded by unidirectional prediction in the prediction direction 0.Adjacent block D has motion vector MvL0_D in the prediction direction 0as a motion vector relative to a reference picture indicated byreference picture-index RefL0_D in the prediction direction 0.

In such a case, as a motion vector predictor of a current block to becoded, for example, a motion vector predictor with which a motion vectorof the current block can be most efficiently coded is selected fromamong motion vector predictor candidates generated from motion vectorsof adjacent blocks A, B, C and D and a motion vector in the temporalmotion vector prediction mode obtained using a co-located block. Then, amotion vector predictor index indicating the selected motion vectorpredictor is added to a bitstream. For example, if motion vector MvL0_Ain the prediction direction 0 of adjacent block A is selected as amotion vector predictor when motion vector MvL0 in the predictiondirection 0 of a current block is to be coded, only value “0” of themotion vector predictor index which indicates that the motion vectorpredictor candidate generated from adjacent block A is used as shown inFIG. 4 is added to a bitstream. Accordingly, the amount of informationon motion vector MvL0 in the prediction direction 0 of the current blockcan be reduced.

Here, FIG. 4 shows an example of a motion vector predictor candidatelist for the prediction direction 0. Further, as shown in FIG. 4 , inthe motion vector predictor designating mode, a candidate with which amotion vector predictor cannot be generated (hereinafter, referred to as“non-available predictor candidate”), and a candidate whose value is thesame as the value of another motion vector predictor candidate(hereinafter, “redundant candidate”) are deleted from motion vectorpredictor candidates. Consequently, the code amount assigned to motionvector predictor indices is reduced by decreasing the number of motionvector predictor candidates. Here, generation of a motion vectorpredictor being impossible means that an adjacent block is (1) a blockcoded by intra prediction, (2) a block outside a boundary of a slice ora picture which includes a current block to be coded, or (3) a blockwhich is not coded yet, for instance.

In the example in FIG. 4 , adjacent block C is coded by intraprediction. Accordingly, a predictor candidate indicated by value “3” ofthe motion vector predictor index is a non-available predictorcandidate, and thus, is deleted from the motion vector predictorcandidate list. Further, a motion vector predictor in the predictiondirection 0 generated from adjacent block D has the same value as thevalue of a motion vector predictor in the prediction direction 0generated from adjacent block A, and thus a predictor candidateindicated by value “4” of the motion vector predictor index is deletedfrom the motion vector predictor candidate list. As a result, the numberof motion vector predictor candidates in the prediction direction 0 iseventually reduced to 3, and the motion vector predictor candidate listsize for the prediction direction 0 is set to 3.

FIG. 5 shows an example of a motion vector predictor candidate list forthe prediction direction 1. In the example shown in FIG. 5 , the numberof motion vector predictor candidates in the prediction direction 1 iseventually reduced to 2 by deleting a non-available predictor candidateand redundant candidates, and the motion vector predictor candidate listsize for the prediction direction 1 is set to 2.

As shown in FIG. 6 , bit strings are assigned to motion vector predictorindices according to the motion vector predictor candidate list size,and are variable-length coded. Further, if the motion vector predictorcandidate list size is 1, a motion vector predictor index is not addedto a bitstream, and a decoding apparatus is caused to estimate that theindex is value 0. In this way, in the motion vector predictordesignating mode, bit strings assigned to motion vector predictorindices are changed according to the motion vector predictor candidatelist size, thereby reducing the code amount.

FIG. 7 is a flowchart showing an example of coding processing in thecase of using the motion vector predictor designating mode.

In step S1001, motion vector predictor candidates in a predictiondirection X are calculated from adjacent blocks and a co-located block(hereafter, referred to as “prediction block candidates”). Here, X isone of the values “0” and “1”, where 0 represents the predictiondirection 0 and 1 represents the prediction direction 1. Motion vectorpredictor candidate sMvLX in the prediction direction X is calculated inaccordance with the following expression, using motion vector MvLX_N andreference picture index RefLX_N of a prediction block candidate andreference picture index RefLX of a current block to be coded.

sMvLX=MvLX_N×(POC(RefLX)−curPOC)/(POC(RefLX_N)−curPOC)   (Expression 1)

Here, POC(RefLX) indicates when in the order a reference pictureindicated by reference picture index RefLX is displayed, POC(RefLX_N)indicates when in the order a reference picture indicated by referencepicture index RefLX_N is displayed, and curPOC indicates when in theorder a current picture to be coded is displayed. It should be notedthat if a prediction block candidate does not have motion vector MvLX_Nin the prediction direction X, motion vector predictor sMvLX iscalculated in accordance with

Expression 2, using motion vector MvL(1−X)_N in the prediction direction(1—X) and reference picture index RefL(1−X)_N.

sMvLX=MvL(1−X)_N×(POC(RefLX)−curPOC)/(POC(RefL(1−X)_N)−curPOC)  (Expression 2)

FIGS. 8A and 8B show examples of calculating motion vector predictorsusing Expressions 1 and 2. It should be noted that as shown byExpressions 1 and 2, if the values of POC(RefLX) and POC(RefLX_N) arethe same, namely, the same picture is referred to, scaling can beskipped.

In step S1002, a redundant candidate and a non-available predictorcandidate are deleted from motion vector predictor candidates in theprediction direction X. In step S1003, the motion vector predictorcandidate list size is set to the number of motion vector predictorcandidates after the deleting processing. In step S1004, a motion vectorpredictor index to be used for coding a motion vector in the predictiondirection X of a current block is determined. In step S1005, thedetermined motion vector predictor index is variable-length coded usinga bit string determined according to the motion vector predictorcandidate list size.

FIG. 9 is a block diagram showing an example of a configuration of amoving picture coding apparatus 1000 which codes a moving picture usingthe motion vector predictor designating mode.

As shown in FIG. 9 , the moving picture coding apparatus 1000 includes asubtraction unit 1001, an orthogonal transform unit 1002, a quantizationunit 1003, an inverse quantization unit 1004, an inverse orthogonaltransform unit 1005, an addition unit 1006, a block memory 1007, a framememory 1008, an intra prediction unit 1009, an inter prediction unit1010, an inter prediction control unit 1011, a picture typedetermination unit 1012, a switch 1013, a motion vector predictorcandidate calculation unit 1014, a colPic memory 1015, and a variablelength coding unit 1016.

In FIG. 9 , the motion vector predictor candidate calculation unit 1014calculates motion vector predictor candidates. Then, the motion vectorpredictor candidate calculation unit 1014 transmits the number ofcalculated motion vector predictor candidates to the variable lengthcoding unit 1016. The variable length coding unit 1016 sets the motionvector predictor candidate list size which is a coding parameter to thenumber of motion vector predictor candidates. Then, the variable lengthcoding unit 1016 variable-length codes motion vector predictor indicesused for coding by assigning thereto bit strings according to the motionvector predictor candidate list size.

FIG. 10 is a flowchart showing an example of decoding processing in thecase of using the motion vector predictor designating mode.

In step S2001, motion vector predictor candidates in the predictiondirection X are calculated from adjacent blocks and a co-located block(prediction block candidates). In step S2002, a redundant candidate anda non-available predictor candidate are deleted from the motion vectorpredictor candidates. In step S2003, the motion vector predictorcandidate list size is set to the number of motion vector predictorcandidates after the deleting processing. In step S2004, a motion vectorpredictor index to be used for decoding a current block is decoded froma bitstream using the motion vector predictor candidate list size. Instep S2005, a motion vector is calculated by adding a motion vectordifference to a motion vector predictor candidate indicated by thedecoded motion vector predictor index, and a predicted image isgenerated using the calculated motion vector, thereby performingdecoding processing.

FIG. 11 is a block diagram showing an example of a configuration of amoving picture decoding apparatus which decodes a moving picture codedusing the motion vector predictor designating mode.

As shown in FIG. 11 , a moving picture decoding apparatus 2000 includesa variable-length decoding unit 2001, an inverse quantization unit 2002,an inverse orthogonal transform unit 2003, an addition unit 2004, ablock memory 2005, a frame memory 2006, an intra prediction unit 2007,an inter prediction unit 2008, an inter prediction control unit 2009, aswitch 2010, a motion vector predictor candidate calculation unit 2011,and a colPic memory 2012.

In FIG. 11 , the motion vector predictor candidate calculation unit 2011calculates motion vector predictor candidates. Then, the motion vectorpredictor candidate calculation unit 2011 transmits the number ofcalculated motion vector predictor candidates to the variable lengthdecoding unit 2001. The variable length decoding unit 2001 sets themotion vector predictor candidate list size which is a decodingparameter to the number of motion vector predictor candidates. Then, thevariable length decoding unit 2001 decodes a motion vector predictorindex included in a bitstream using the motion vector predictorcandidate list size.

FIG. 12 shows syntax used when a motion vector predictor index is addedto a bitstream. In FIG. 12 , inter_pred_flag indicates a predictiondirection flag for inter prediction, mvp_jdx indicates a motion vectorpredictor index, and NumMVPCand indicates the motion vector predictorcandidate list size. NumMVPCand is set to the number of motion vectorpredictor candidates after deleting a non-available predictor candidateand a redundant candidate from the motion vector predictor candidates.

As described above, a moving picture is coded or decoded using themotion vector predictor designating mode.

However, in the above motion vector predictor designating mode, acandidate for a motion vector predictor to be used when coding a motionvector of a current block to be coded is calculated from a motion vectorused for a block adjacent to the current block, for instance. Thus, forexample, if an adjacent block is a moving object area and a currentblock to be coded is a static area, a motion vector predictor candidateof the current block is influenced by the moving object area. For thisreason, a motion vector predictor for efficiently coding a motion vectorof a current block which has a comparatively small value may not beincluded in motion vector predictor candidates, and thus codingefficiency may fall.

In view of this, an object of the present invention is to provide amoving picture coding method which improves coding efficiency by addinga motion vector predictor for a static area to motion vector predictorcandidate lists.

In view of this, a moving picture coding method according to an aspectof the present invention is a moving picture coding method forcalculating a motion vector predictor to be used when coding a motionvector of a current block to be coded, and coding the current block, togenerate a bitstream, the method including: deriving each of one or morefirst motion vector predictor candidates, based on a motion vector usedfor coding a block spatially or temporally adjacent to the currentblock; deriving one or more second motion vector predictor candidateseach having a predetermined vector as a motion vector; selecting, fromamong the one or more first motion vector predictor candidates and theone or more second motion vector predictor candidates, the motion vectorpredictor to be used for coding the motion vector of the current block;and adding an index for identifying the motion vector predictor to thebitstream.

According to this, a motion vector predictor candidate which has apredetermined vector as a motion vector can be derived as the secondmotion vector predictor candidate. Thus, a motion vector predictorcandidate which has a static area motion vector, for example, can bederived as the second motion vector predictor candidate. Consequently, acurrent block to be coded which has predetermined motion can be codedefficiently, which improves coding efficiency.

For example, the predetermined vector may be a zero vector.

According to this, since the predetermined vector is a zero vector, amotion vector predictor candidate having a static area motion vector canbe derived. Therefore, if the current block is a static area, it ispossible to improve coding efficiency.

For example, the moving picture coding method may further include:determining a maximum number of motion vector predictor candidates; anddetermining whether a total number of the one or more first motionvector predictor candidates which have been derived is smaller than themaximum number, wherein when deriving the one or more second motionvector predictor candidates, the one or more second motion vectorpredictor candidate may be derived when it is determined that the totalnumber of one or more first motion vector predictor candidates issmaller than the maximum number.

According to this, a second motion vector predictor candidate can bederived if it is determined that the number of first motion vectorpredictor candidates is smaller than the maximum number. Thus, it ispossible to increase the number of motion vector predictor candidates ina range which does not exceed the maximum number, and improve codingefficiency.

For example, when adding the index, the index may be coded using thedetermined maximum number, and the coded index may be added to thebitstream.

According to this, an index for identifying a motion vector predictorcandidate can be coded using the determined maximum number.Specifically, an index can be coded without depending on the number ofmotion vector predictor candidates actually derived. Thus, even ifinformation necessary for deriving a motion vector predictor candidate(for example, information of a co-located block and the like) is lost, adecoding apparatus can decode an index, and error resistance can beimproved. Further, the decoding apparatus can decode an index, withoutdepending on the number of motion vector predictor candidates actuallyderived. Specifically, the decoding apparatus can decode an index,without waiting for derivation of a motion vector predictor candidate.In other words, it is possible to generate a bitstream for whichderiving a motion vector predictor candidate and decoding an index canbe performed in parallel.

For example, when adding the index, information indicating thedetermined maximum number may be further added to the bitstream.

According to this, information indicating the determined maximum numbercan be added to a bitstream. Therefore, the maximum number can bechanged in a suitable unit, which allows coding efficiency to beimproved.

For example, when deriving the one or more first motion vector predictorcandidates, a motion vector used for coding a block may be derived asthe first motion vector predictor candidate, the block being spatiallyadjacent to the current block, and not being (i) a block coded by intraprediction, (ii) a block located outside a boundary of a slice or apicture which includes the current block, or (iii) a block which is notcoded yet.

According to this, the first motion vector predictor candidate can bederived based on a block suitable for obtaining a motion vectorpredictor candidate.

For example, when deriving the first motion vector predictor candidates,a motion vector predictor candidate may be derived as the first motionvector predictor candidate, the motion vector predictor candidate havinga motion vector different from a motion vector of any of the one or morefirst motion vector predictor candidates which have already beenderived.

According to this, a motion vector predictor candidate having the samemotion vector as a motion vector of any of the first motion vectorpredictor candidates which have already been derived can be excludedfrom the first motion vector predictor candidates. As a result, thenumber of second motion vector predictor candidates can be increased,and the types of motion vectors selectable as motion vector predictorcandidates can be increased. Thus, it is possible to further improvecoding efficiency.

For example, the moving picture coding method may further include:switching between first coding processing conforming to a first standardand second coding processing conforming to a second standard; andadding, to the bitstream, identification information indicating thefirst standard or the second standard to which a corresponding one ofthe first coding processing and the second coding processing after theswitching conforms, wherein when the switch to the first codingprocessing is made, deriving the one or more first motion vectorpredictor candidates, deriving the one or more second motion vectorpredictor candidates, selecting the motion vector predictor, and addingthe index may be performed as the first coding processing.

According to this, it is possible to switch between the first codingprocessing conforming to the first standard and the second codingprocessing conforming to the second standard.

A moving picture decoding method according to an aspect of the presentinvention is a moving picture decoding method for calculating a motionvector predictor to be used when decoding a motion vector of a currentblock to be decoded which is included in a bitstream, and decoding thecurrent block, the method including: deriving each of one or more firstmotion vector predictor candidates, based on a motion vector used fordecoding a block spatially or temporally adjacent to the current block;deriving one or more second motion vector predictor candidates eachhaving a predetermined vector as a motion vector; obtaining an index foridentifying one of one or more motion vector predictor candidates fromthe bitstream; and selecting, based on the obtained index, the motionvector predictor to be used when decoding the current block, from amongthe one or more first motion vector predictor candidates and the one ormore second motion vector predictor candidates.

According to this, a motion vector predictor candidate having thepredetermined vector as a motion vector can be derived as the secondmotion vector predictor candidate. Thus, for example, a motion vectorpredictor candidate having a static area motion vector, for instance,can be derived as the second motion vector predictor candidate.Consequently, a bitstream in which a block having predetermined motionis coded efficiently can be decoded appropriately, and thus it ispossible to appropriately decode a bitstream for which coding efficiencyhas been improved.

For example, the predetermined vector may be a zero vector.

According to this, since the predetermined vector is a zero vector, itis possible to derive a motion vector predictor candidate having astatic area motion vector. Therefore, it is possible to appropriatelydecode a bitstream for which coding efficiency has been improved.

For example, the moving picture decoding method may further include:determining a maximum number of the motion vector predictor candidates;and determining whether a total number of the one or more first motionvector predictor candidates which have been derived is smaller than themaximum number, wherein when deriving the one or more second motionvector predictor candidates, the one or more second motion vectorpredictor candidates may be derived when it is determined that the totalnumber of one or more first motion vector predictor candidates issmaller than the maximum number.

According to this, a second motion vector predictor candidate can bederived if it is determined that the number of first motion vectorpredictor candidates is smaller than the maximum number. Therefore, thenumber of motion vector predictor candidates can be increased in a rangewhich does not exceed the maximum number, and thus it is possible toappropriately decode a bitstream for which coding efficiency has beenimproved.

For example, when obtaining the index, the index may be obtained bydecoding, using the determined maximum number, the index coded and addedto the bitstream.

According to this, an index for identifying a motion vector predictorcandidate can be decoded using the determined maximum number.Specifically, an index can be decoded without depending on the number ofmotion vector predictor candidates actually derived. Therefore, an indexcan be decoded even if information necessary for deriving a motionvector predictor candidate (for example, information of a co-locatedblock and the like) is lost, which enables error resistance to beimproved. Furthermore, it is possible to decode an index without waitingfor derivation of a motion vector predictor candidate, and also derive amotion vector predictor candidate and decode an index in parallel.

For example, when determining the maximum number, the maximum number maybe determined based on information indicating a maximum number and addedto the bitstream.

According to this, the maximum number can be determined based oninformation added to a bitstream. Thus, it is possible to decode animage coded by changing the maximum number in a suitable unit.

For example, when deriving the one or more first motion vector predictorcandidates, a motion vector used for decoding a block may be derived asthe first motion vector predictor candidate, the block being spatiallyadjacent to the current block, and not being (i) a block decoded byintra prediction, (ii) a block located outside a boundary of a slice ora picture which includes the current block, or (iii) a block which isnot decoded yet.

According to this, the first motion vector predictor candidate can bederived based on a block suitable for obtaining a motion vectorpredictor candidate.

For example, when deriving the first motion vector predictor candidates,a motion vector predictor candidate may be derived as the first motionvector predictor candidate, the motion vector predictor candidate havinga motion vector different from a motion vector of any of the one or morefirst motion vector predictor candidates which have already beenderived.

According to this, a motion vector predictor candidate having the samemotion vector as a motion vector of any of the first motion vectorpredictor candidates which have already been derived can be excludedfrom the first motion vector predictor candidates. As a result, thenumber of second motion vector predictor candidates can be increased,and the types of combinations of a prediction direction, a motionvector, and a reference picture index, which are selectable as motionvector predictor candidates, can be increased. Therefore, it is possibleto appropriately decode a bitstream for which coding efficiency has beenfurther improved.

For example, the moving picture decoding method may further includeswitching between first decoding processing conforming to a firststandard and second decoding processing conforming to a second standard,according to identification information indicating the first standard orthe second standard and added to the bitstream, wherein when the switchto the first decoding processing is made, deriving the one or more firstmotion vector predictor candidates, deriving the one or more secondmotion vector predictor candidates, obtaining the index, and selectingthe motion vector predictor may be performed as the first decodingprocessing.

According to this, it is possible to switch between the first decodingprocessing conforming to the first standard and the second decodingprocessing conforming to the second standard.

It should be noted that these general and specific aspects may beimplemented using a system, a method, an integrated circuit, a computerprogram, a computer-readable recording medium such as a CD-ROM, or anycombination of systems, methods, integrated circuits, computer programsor recording media.

The following is a specific description of a moving picture codingapparatus and a moving picture decoding apparatus according to an aspectof the present invention, with reference to the drawings.

Each of the exemplary embodiments described below shows a general orspecific example. The numerical values, shapes, materials, constituentelements, the arrangement and connection of the constituent elements,steps, the processing order of the steps and the like described in thefollowing embodiments are mere examples, and thus do not limit the scopeof the appended Claims and their equivalents. Therefore, among theconstituent elements in the following exemplary embodiments, constituentelements not recited in any one of the independent claims are describedas arbitrary constituent elements.

Embodiment 1

FIG. 13 is a block diagram showing a configuration of a moving picturecoding apparatus 100 according to at Embodiment 1.

As shown in FIG. 13 , the moving picture coding apparatus 100 includes asubtraction unit 101, an orthogonal transform unit 102, a quantizationunit 103, an inverse quantization unit 104, an inverse orthogonaltransform unit 105, an addition unit 106, a block memory 107, a framememory 108, an intra prediction unit 109, an inter prediction unit 110,an inter prediction control unit 111, a picture type determination unit112, a switch 113, a motion vector predictor candidate calculation unit114, a colPic memory 115, and a variable length coding unit 116.

The subtraction unit 101 generates prediction error data by subtracting,for each block, predicted image data from input image data included inan input image sequence. The orthogonal transform unit 102 transformsthe generated prediction error data from an image domain into afrequency domain. The quantization unit 103 performs quantizationprocessing on the prediction error data which has been transformed intothe frequency domain.

The inverse quantization unit 104 performs inverse quantizationprocessing on the prediction error data on which quantization processinghas been performed by the quantization unit 103. The inverse orthogonaltransform unit 105 transforms the prediction error data on which inversequantization processing has been performed, from the frequency domaininto the image domain.

The addition unit 106 generates reconstructed image data by adding, foreach block to be coded, predicted image data and the prediction errordata on which inverse quantization processing has been performed by theinverse orthogonal transform unit 105. The block memory 107 storesreconstructed image data on a block-by-block basis. The frame memory 108stores reconstructed image data on a frame-by-frame basis.

The picture type determination unit 112 determines which of picturetypes, namely, I-picture, B-picture, and P-picture, an input image datais to be coded as. Then, the picture type determination unit 112generates picture type information. The intra prediction unit 109generates intra-predicted image data of a current block to be coded byperforming intra prediction using the reconstructed image data in blockunits stored in the block memory 107. The inter prediction unit 110generates inter-predicted image data of a current block to be coded byperforming inter prediction using the reconstructed image data in frameunits stored in the frame memory 108, and a motion vector derived bymotion detection and the like.

The switch 113 outputs the intra-predicted image data generated by theintra prediction unit 109 to the subtraction unit 101 and the additionunit 106 as predicted image data of the current block, if intraprediction coding is performed on the current block. On the other hand,the switch 113 outputs the inter-predicted image data generated by theinter prediction unit 110 to the subtraction unit 101 and the additionunit 106 as predicted image data of the current block if the interprediction coding is performed on the current block.

The motion vector predictor candidate calculation unit 114 derivesmotion vector predictor candidates in the motion vector predictordesignating mode, using motion vectors of blocks adjacent to the currentblock and the like and colPic information such as information of amotion vector of a co-located block stored in the colPic memory 115.Then, the motion vector predictor candidate calculation unit 114calculates the number of motion vector predictor candidates using themethod described below. Further, the motion vector predictor candidatecalculation unit 114 assigns the values of the motion vector predictorindex to the derived motion vector predictor candidates. Then, themotion vector predictor candidate calculation unit 114 sends the motionvector predictor candidates and the motion vector predictor indices tothe inter prediction control unit 111. Further, the motion vectorpredictor candidate calculation unit 114 transmits the number ofcalculated motion vector predictor candidates to the variable lengthcoding unit 116.

The inter prediction control unit 111 controls the inter prediction unit110 so as to cause the inter prediction unit 110 to perform interprediction coding, using the inter-predicted image generated using amotion vector derived by motion detection. Further, the inter predictioncontrol unit 111 selects, using the method described below, a motionvector predictor candidate most suitable for coding a motion vector usedfor inter prediction coding. Then, the inter prediction control unit 111sends a motion vector predictor index corresponding to the selectedmotion vector predictor candidate, and prediction error information(motion vector difference) to the variable length coding unit 116.Furthermore, the inter prediction control unit 111 transfers colPicinformation including information of a motion vector of the currentblock and the like to the colPic memory 115.

The variable length coding unit 116 performs variable length codingprocessing on prediction error data on which quantization processing hasbeen performed, a prediction direction flag, picture type information,and a motion vector difference, thereby generating a bitstream.Furthermore, the variable length coding unit 116 sets the motion vectorpredictor candidate list size to the number of motion vector predictorcandidates. Then, the variable length coding unit 116 variable-lengthcodes the motion vector predictor index used for coding a motion vectorby assigning, thereto, a bit string according to the motion vectorpredictor candidate list size.

FIG. 14 is a flowchart showing processing operation of the movingpicture coding apparatus 100 according to Embodiment 1.

In step S101, the inter prediction control unit 111 determines aprediction direction, a reference picture index, and a motion vector ofa current block to be coded by motion detection. Here, in motiondetection, a difference value indicating a difference between a currentblock to be coded in a picture to be coded and a block in a referencepicture is calculated, and a block in the reference picture with whichthe difference value is smallest is determined as a reference block.Then, a motion vector is obtained based on the position of a currentblock to be coded and the position of a reference block position usingthe method for obtaining a motion vector, for instance. Further, theinter prediction control unit 111 performs motion detection on each ofreference pictures in the prediction directions 0 and 1, and determineswhether to select the prediction direction 0, the prediction direction 1or bidirectional prediction using, for example, the following expressionfor an R-D optimization model, or the like.

Cost=D+λ×R   (Expression 3)

In Expression 3, D denotes coding distortion, and for instance, a sum ofabsolute differences are used therefor each of which is an absolutedifference between a pixel value obtained by coding and decoding acurrent block using a predicted image generated using a certain motionvector and an original pixel value of the current block. R denotes agenerated code amount, and a code amount necessary to code a motionvector used for generating a predicted image is used therefor. Further,λ denotes a Lagrange undetermined multiplier.

In step S102, the motion vector predictor candidate calculation unit 114derives motion vector predictor candidates from blocks adjacent to thecurrent block and a co-located block thereof. Further, the motion vectorpredictor candidate calculation unit 114 calculates the motion vectorpredictor candidate list size according to the method described below.

For example, in the case as shown in FIG. 3 , the motion vectorpredictor candidate calculation unit 114 selects motion vectors whichadjacent blocks A, B, C, and D have, as motion vector predictorcandidates of the current block. Furthermore, the motion vectorpredictor candidate calculation unit 114 calculates a motion vector, forinstance, which is calculated using a temporal prediction mode from amotion vector of the co-located block, as a motion vector predictorcandidate.

The motion vector predictor candidate calculation unit 114 assignsmotion vector predictor indices to the motion vector predictorcandidates in the prediction directions 0 and 1, as shown in (a) in FIG.15 and (a) in FIG. 16 . Then, the motion vector predictor candidatecalculation unit 114 calculates motion vector predictor candidate listsas shown in (b) in FIG. 15 and (b) in FIG. 16 , and the sizes of themotion vector predictor candidate lists by deleting a non-availablepredictor candidate and a redundant candidate and adding a zerocandidate, using the method described below.

The smaller a value of a motion vector predictor index is, the shortercode is assigned to the motion vector predictor index. Specifically, ifthe value of a motion vector predictor index is small, the amount ofinformation necessary for the motion vector predictor index is small. Onthe other hand, if the value of a motion vector predictor index islarge, the amount of information necessary for the motion vectorpredictor index is large. Thus, coding efficiency is increased byassigning a motion vector predictor index having a small value to amotion vector predictor candidate having a high possibility of becominga motion vector, predictor with high precision.

In view of this, the motion vector predictor candidate calculation unit114 may measure, for each motion vector predictor candidate, the numberof times at which the motion vector predictor candidate has beenselected as a motion vector predictor, and assign a motion vectorpredictor index having a small value to a motion vector predictorcandidate whose number of times at which the candidate has been selectedis large, for example. Specifically, it is possible to consideridentifying a motion vector predictor selected in an adjacent block, andin coding a current block, assigning a motion vector predictor indexhaving a small value to the identified motion vector predictorcandidate.

It should be noted that if an adjacent block does not have informationof a motion vector and the like (if the adjacent block is coded by intraprediction, if the adjacent block is located, for instance, outside aboundary of a picture or a slice, if the adjacent block is not codedyet, or the like), the adjacent block cannot be utilized as a motionvector predictor candidate.

In the present embodiment, a candidate that cannot be utilized as amotion vector predictor candidate is referred to as a non-availablepredictor candidate. A candidate that can be utilized as a motion vectorpredictor candidate is referred to as an available predictor candidate.Further, among a plurality of motion vector predictor candidates, acandidate whose value is the same as any one of the other motion vectorpredictors is referred to as a redundant candidate.

In the case of FIG. 3 , adjacent block C is a block coded by intraprediction, and thus is assumed to be a non-available predictorcandidate. Further, motion vector predictor sMvL0_D in the predictiondirection 0 generated from adjacent block D has the same value as thevalue of motion vector predictor MvL0_A in the prediction direction 0generated from adjacent block A, and thus is assumed to be a redundantcandidate.

In step S103, the inter prediction control unit 111 determines a valueof a motion vector predictor index to be used for coding a motion vectorin the prediction direction X by using the method described below.

In step S104, the variable length coding unit 116 variable length-codesmotion vector predictor indices of motion vector predictor candidates tobe used for coding motion vectors in the prediction direction X byassigning thereto bit strings according to the motion vector predictorcandidate list size as shown in FIG. 6 .

In the present embodiment, as shown in (a) in FIG. 15 and (a) in FIG. 16, “0” is assigned as a value of a motion vector predictor indexcorresponding to adjacent block A. “1” is assigned as a value of amotion vector predictor index corresponding to adjacent block B. “2” isassigned as a value of a motion vector predictor index corresponding toa co-located block. “3” is assigned as a value of a motion vectorpredictor index corresponding to adjacent block C. “4” is assigned as avalue of a motion vector predictor index corresponding to adjacent blockD.

It should be noted that the way to assign motion vector predictorindices is not necessarily limited to this example. For example, if azero candidate is added using the method described below, the variablelength coding unit 116 may assign a small value to a motion vectorpredictor candidate which is not the added vector, and a large value tothe zero candidate. Specifically, the variable length coding unit 116may preferentially assign a motion vector predictor block index having asmall value to a motion vector predictor candidate which is not theadded vector.

Further, motion vector predictor candidates are not necessarily limitedto be at the positions of adjacent blocks A, B, C, and D. For example,an adjacent block located on bottom-left adjacent block D, for instance,may be used to obtain a motion vector predictor candidate. Further, allthe adjacent blocks do not necessarily need to be used to obtain motionvector predictor candidates. For example, only adjacent blocks A and Bmay be used to obtain motion vector predictor candidates. Alternatively,adjacent blocks may be sequentially scanned by using, for instance,adjacent block A if adjacent block D is a non-available predictorcandidate.

Further, in the present embodiment, although the variable length codingunit 116 adds a motion vector predictor index to a bitstream in stepS104 in FIG. 14 , a motion vector predictor index does not necessarilyneed to be added to a bitstream. For example, if the motion vectorpredictor candidate list size is 1, the variable length coding unit 116may not add a motion vector predictor index to a bitstream. Accordingly,the amount of information can be reduced by that of the motion vectorpredictor index.

FIG. 17 is a flowchart showing detailed processing of step S102 in FIG.14 . Specifically, FIG. 17 shows a method for calculating motion vectorpredictor candidates and the motion vector predictor candidate listsize. The following is a description of FIG. 17 .

In step S111, the motion vector predictor candidate calculation unit 114determines, using the method described below, whether a prediction blockcandidate [N] is an available predictor candidate.

Here, N is an index value for denoting each prediction block candidate.In the present embodiment, N is one of the values from 0 to 4.Specifically, adjacent block A in FIG. 3 is assigned to a predictionblock candidate [0]. Adjacent block B in FIG. 3 is assigned to aprediction block candidate [1]. A co-located block is assigned to aprediction block candidate [2]. Adjacent block C in FIG. 3 is assignedto a prediction block candidate [3]. Adjacent block D in FIG. 3 isassigned to a prediction block candidate [4].

In step S112, the motion vector predictor candidate calculation unit 114derives a motion vector predictor candidate in the prediction directionX from the prediction block candidate [N] using Expressions 1 and 2above, and adds the derived candidate to a corresponding one of themotion vector predictor candidate lists.

In step S113, the motion vector predictor candidate calculation unit 114searches for and deletes a non-available predictor candidate and aredundant candidate from the motion vector predictor candidate lists, asshown in FIGS. 15 and 16 .

In step S114, the motion vector predictor candidate calculation unit 114adds a zero candidate to a corresponding one of the motion vectorpredictor candidate lists by using the method described below. Here,when a zero candidate is added, the motion vector predictor candidatecalculation unit 114 may reassign values of motion vector predictorindices so as to preferentially assign a small motion vector predictorindex to a motion vector predictor candidate which is not the addedvector. Specifically, the motion vector predictor candidate calculationunit 114 may reassign values of motion vector predictor indices so as toassign a motion vector predictor index having a large value to the zerocandidate. Accordingly, the amount of coding motion vector predictorindices can be reduced.

In step S115, the motion vector predictor candidate calculation unit 114sets the motion vector predictor candidate list size to the number ofmotion vector predictor candidates after the zero candidate is added instep S114. In the examples of FIGS. 15 and 16 , by using the methoddescribed below, “4” is calculated as the number of motion vectorpredictor candidates in the prediction direction 0, and the motionvector predictor candidate list size for the prediction direction 0 isset to “4”. Further, “3” is calculated as the number of motion vectorpredictor candidates in the prediction direction 1, and the motionvector predictor candidate list size for the prediction direction 1 isset to “3”.

In this way, if the number of motion vector predictor candidates has notreached the maximum number of motion vector predictor candidates, themotion vector predictor candidate calculation unit 114 can improvecoding efficiency by adding the zero candidate.

FIG. 18 is a flowchart showing detailed processing of step S111 in FIG.17 . Specifically, FIG. 18 shows a method for determining whether apredicted block candidate [N] is an available predictor candidate. Thefollowing is a description of FIG. 18 .

In step S121, the motion vector predictor candidate calculation unit 114determines whether a prediction block candidate [N] is (1)intra-predicted, (2) located outside a boundary of a slice or a picturewhich includes a current block to be coded, or (3) is not coded yet.

If the determination result in step S121 is true here (Yes in S121), themotion vector predictor candidate calculation unit 114 sets theprediction block candidate [N] as a non-available predictor candidate instep S122. On the other hand, if the determination result in step S121is false (No in S121), the motion vector predictor candidate calculationunit 114 sets the prediction block candidate [N] as an availablepredictor candidate in step S123.

FIG. 19 is a flowchart showing detailed processing of step S114 in FIG.17 . Specifically, FIG. 19 shows a method for adding a zero candidate.The following is a description of FIG. 19 .

In step S131, the motion vector predictor candidate calculation unit 114determines whether the number of motion vector predictor candidates issmaller than the maximum number of motion vector predictor candidates.Specifically, the motion vector predictor candidate calculation unit 114determines whether the number of motion vector predictor candidates hasnot reached the maximum number of motion vector predictor candidates.

Here, if the determination result in step S131 is true (Yes in S131),the motion vector predictor candidate calculation unit 114 determines instep S132 whether the zero candidate having a motion vector whose valueis “0” is not a redundant candidate. Here, if the determination resultin step S132 is true (No in S132), the motion vector predictor candidatecalculation unit 114 assigns a value of a motion vector predictor indexto the zero candidate, and adds the zero candidate to a correspondingone of the motion vector predictor candidate lists in step S133.Furthermore, in step S134, the motion vector predictor candidatecalculation unit 114 adds 1 to the number of motion vector predictorcandidates.

On the other hand, if the determination result in step S131 or step S132is false (No in S131 or Yes in S132), zero candidate adding processingends. Specifically, if the number of motion vector predictor candidateshas reached the maximum number of motion vector predictor candidates, orif the zero candidate is a redundant candidate, zero candidate addingprocessing ends.

FIG. 20 is a flowchart showing detailed processing of step S103 in FIG.14 . Specifically, FIG. 20 shows processing regarding selection of amotion vector predictor candidate. The following is a description ofFIG. 20 .

In step S141, as initialization, the inter prediction control unit 111sets motion vector predictor candidate index mvp_idx to 0, and sets thesmallest motion vector difference to the maximum value.

In step S142, the inter prediction control unit 111 determines whetherthe value of motion vector predictor candidate index mvp_idx is smallerthan the number of motion vector predictor candidates. Specifically, theinter prediction control unit 111 determines whether motion vectordifferences of all the motion vector predictor candidates have beencalculated.

Here, if there still remains a motion vector predictor candidate forwhich calculation has not been performed (Yes in S142), the interprediction control unit 111 calculates a motion vector difference bysubtracting a motion vector predictor candidate from a vector obtainedas a result of motion detection (motion detection resultant vector) instep S143.

In step S144, the inter prediction control unit 111 determines whetherthe motion vector difference obtained in step S143 has a value smallerthan the smallest motion vector difference.

Here, if the determination result in step S144 is true (Yes in S144),the inter prediction control unit 111 updates the smallest motion vectordifference and the value of a motion vector predictor index in stepS145. On the other hand, if the determination result in step S144 isfalse (No in S144), the inter prediction control unit 111 does notupdate the smallest motion vector difference and the value of a motionvector predictor index.

In step S146, the inter prediction control unit 111 updates a motionvector predictor candidate index by incrementing by +1, and returningback to step S142, the inter prediction control unit 111 determineswhether a next motion vector predictor candidate is present.

On the other hand, if it is determined in step S2 that a motion vectordifference has been calculated for all the motion vector predictorcandidates (No in S142), the inter prediction control unit 111 fixes, instep S147, the smallest motion vector difference and the motion vectorpredictor index which are set at last.

In this way, according to the moving picture coding apparatus 100according to the present embodiment, it is possible to improve codingefficiency by adding a static area motion vector predictor to acorresponding one of the motion vector predictor candidate lists. Morespecifically, if the number of motion vector predictor candidates hasnot reached the maximum number of motion vector predictor candidates,the moving picture coding apparatus 100 can improve coding efficiency byadding a zero candidate having a motion vector whose value is “0” as amotion vector predictor candidate.

It should be noted that although the present embodiment shows an examplein which the moving picture coding apparatus 100 adds a zero candidatehaving a motion vector whose value is “0” as a static area motion vectorto the motion vector predictor candidates, the present invention is notnecessarily limited to this.

For example, the moving picture coding apparatus 100 may add, to themotion vector predictor candidates, a motion vector which is slightlylarger or smaller than a motion vector (0, 0) whose value is “0”, suchas a motion vector (0, 1), for considerations of slight camera shakeduring video shooting.

Further, the moving picture coding apparatus 100 may add an offsetparameter (OffsetX, OffsetY) to a header of a sequence, a picture, or aslice, for example, and add a motion vector (OffsetX, OffsetY) to themotion vector predictor candidates.

Further, when creating the motion vector predictor candidate lists, forexample, the moving picture coding apparatus 100 may set a motion vector(0, 0) whose value is “0” as an initial value of all the motion vectorpredictor candidates on the motion vector predictor candidate lists, asshown in (a) in FIG. 21 . In this case, when the moving picture codingapparatus 100 calculates a motion vector predictor candidate and addsthe candidate to a corresponding one of the motion vector predictorcandidate lists, the motion vector (0, 0) which is an initial value willbe overwritten. Then, the moving picture coding apparatus 100 determineswhether the calculated motion vector predictor candidate is anon-available predictor candidate or a redundant candidate, before thecalculated motion vector predictor candidate is added to thecorresponding motion vector predictor candidate list. Accordingly, ifthere is a non-available predictor candidate or a redundant candidate,the motion vector (0, 0) which is an initial value remains in the motionvector predictor candidate list, as shown in FIG. 21 (b), for example.It is also possible to add a zero candidate as a motion vector predictorcandidate by using such a method.

Although the present embodiment describes an example in which the motionvector predictor designating mode is used in which motion vectorpredictor candidates are generated from blocks adjacent to a currentblock to be coded, and a motion vector of the current block is coded,the present embodiment is not necessarily limited to this. For example,a direct mode or a skip mode may be used. In the direct mode or the skipmode, a motion vector difference may not be added to a bitstream byselecting a motion vector predictor from among the motion vectorpredictor candidates created as shown in (b) in FIG. 15 and (b) in FIG.16 , and directly generating a predicted image using the selected motionvector predictor as a motion vector.

Embodiment 2

The present embodiment is a modification of the moving picture codingapparatus according to Embodiment 1 above. The following is a specificdescription of a moving picture coding apparatus according to Embodiment2.

FIG. 22 is a block diagram showing a configuration of a moving picturecoding apparatus 200 according to Embodiment 2. The moving picturecoding apparatus 200 generates a bitstream by coding an image on ablock-by-block basis. The moving picture coding apparatus 200 includes amotion vector predictor candidate derivation unit 210, a predictioncontrol unit 220, and a coding unit 230.

The motion vector predictor candidate derivation unit 210 corresponds tothe motion vector predictor candidate calculation unit 114 in Embodiment1 above. The motion vector predictor candidate derivation unit 210derives motion vector predictor candidates. Then, the motion vectorpredictor candidate derivation unit 210 generates motion vectorpredictor candidate lists in which, for example, each of the derivedmotion vector predictor candidates is associated with an index(hereafter, referred to as “motion vector predictor index”) foridentifying the motion vector predictor candidate.

A motion vector predictor candidate is a candidate for a motion vectorto be used for coding a current block to be coded.

As shown in FIG. 22 , the motion vector predictor candidate derivationunit 210 includes a first derivation unit 211 and a second derivationunit 212.

More specifically, the first derivation unit 211 derives one or morefirst motion vector predictor candidates, each based on a motion vectorused for coding a block spatially or temporally adjacent to a currentblock to be coded, for example. Then, for example, the first derivationunit 211 registers, into the motion vector predictor candidate lists,the one or more first motion vector predictor candidates derived in thisway, each in association with a motion vector predictor index.

A spatially adjacent block is a block in a picture which includes acurrent block to be coded, and is a block adjacent to the current block.Specifically, examples of spatially adjacent blocks are adjacent blocksA to D shown in FIG. 3 .

A temporally adjacent block is a block included in a picture differentfrom a picture which includes a current block to be coded, and is ablock corresponding to the current block. Specifically, an example of atemporally adjacent block is a co-located block.

It should be noted that a temporally adjacent block does not necessarilyneed to be a block at the same position as that of a current block to becoded (co-located block). For example, a temporally adjacent block maybe a block adjacent to a co-located block.

It should be noted that, for example, the first derivation unit 211 mayderive, as the first motion vector predictor candidate, a motion vectorused for coding a block that is a block spatially adjacent to a currentblock to be coded, and is not a block which is a non-available predictorcandidate. A block which is a non-available predictor candidate is ablock coded by intra prediction, a block located outside a boundary of aslice or a picture which includes a current block to be coded, or ablock which is not coded yet. Accordingly, the first derivation unit 211can derive the first motion vector predictor candidate from a blocksuitable for obtaining a motion vector predictor candidate.

The second derivation unit 212 derives one or more second motion vectorpredictor candidates each having a predetermined vector as a motionvector. The predetermined vector may be a zero vector as in Embodiment1, for example. Accordingly, the second derivation unit 212 can derive amotion vector predictor candidate having a static area motion vector.Therefore, the moving picture coding apparatus 200 can improve codingefficiency if a current block to be coded is a static area. It should benoted that the predetermined vector does not necessarily need to be azero vector.

Furthermore, the second derivation unit 212 registers, into the motionvector predictor candidate lists, the one or more second motion vectorpredictor candidates derived in this way, each in association with amotion vector predictor index, for example. At this time, the secondderivation unit 212 may register each second motion vector predictorcandidate into a corresponding one of the motion vector predictorcandidate lists, such that a motion vector predictor index having avalue smaller than that for the second motion vector predictorcandidates is assigned to each first motion vector predictor candidate,as in Embodiment 1. Accordingly, if there is a high possibility that thefirst motion vector predictor candidate will be selected as a motionvector predictor candidate to be used for coding rather than the secondmotion vector predictor candidates, the moving picture coding apparatus200 can reduce the code amount, and improve coding efficiency.

The prediction control unit 220 selects a motion vector predictorcandidate to be used for coding a current block to be coded, from amongthe one ore more first motion vector predictor candidates and the oneore more second motion vector predictor candidates which have beenderived. Specifically, the prediction control unit 220 selects, from themotion vector predictor candidate lists, a motion vector predictorcandidate to be used for coding the current block.

The coding unit 230 adds an index (motion vector predictor index) foridentifying the selected motion vector predictor candidate to abitstream. For example, the coding unit 230 codes a motion vectorpredictor index, using the sum of the number of derived first motionvector predictor candidates and the number of derived second motionvector predictor candidates (the number of motion vector predictorcandidates), and adds the coded motion vector predictor index to abitstream.

Next is a description of various operations of the moving picture codingapparatus 200 constituted as described above.

FIG. 23 is a flowchart showing processing operation of the movingpicture coding apparatus 200 according to Embodiment 2.

First, the first derivation unit 211 derives one or more first motionvector predictor candidates (S201). Next, the second derivation unit 212derives one or more second motion vector predictor candidates (S202).

Then, the prediction control unit 220 selects a motion vector predictorto be used for coding a current block to be coded from among the one ormore first motion vector predictor candidates and the one or more secondmotion vector predictor candidate (S203). For example, the predictioncontrol unit 220 selects a motion vector predictor with which a motionvector difference is the smallest from the motion vector predictorcandidate lists, as in Embodiment 1.

Finally, the coding unit 230 adds an index for identifying the selectedmotion vector predictor candidate to a bitstream (S204).

As described above, according to the moving picture coding apparatus 200according to the present embodiment, the second motion vector predictorcandidate having a predetermined vector as a motion vector can bederived. Therefore, the moving picture coding apparatus 200 can derivethe second motion vector predictor candidate having a static area motionvector or the like, for example. Specifically, the moving picture codingapparatus 200 can efficiently code a current block to be coded which haspredetermined motion, and thus can improve coding efficiency.

It should be noted that when creating the motion vector predictorcandidate lists, the moving picture coding apparatus 200 may set thesecond motion vector predictor candidate as an initial value of all themotion vector predictor candidates on the motion vector predictorcandidate lists, as in Embodiment 1 above. In this case, the motionvector predictor candidate derivation unit 210 derives the second motionvector predictor candidate before the first motion vector predictorcandidate. It is also possible to set the second motion vector predictorcandidate as a motion vector predictor candidate by using such a method.

Embodiment 3

FIG. 24 is a block diagram showing a configuration of a moving picturedecoding apparatus 300 according to Embodiment 2.

As shown in FIG. 24 , the moving picture decoding apparatus 300 includesa variable length decoding unit 301, an inverse quantization unit 302,an inverse orthogonal transform unit 303, an addition unit 304, a blockmemory 305, a frame memory 306, an intra prediction unit 307, an interprediction unit 308, an inter prediction control unit 309, a switch 310,a motion vector predictor candidate calculation unit 311, and a colPicmemory,312.

The variable length decoding unit 301 performs variable length decodingprocessing on an input bitstream, and generates picture typeinformation, a prediction direction flag, a quantization coefficient,and a motion vector difference. Further, the variable length decodingunit 301 performs variable length decoding processing on a motion vectorpredictor index, using the number of motion vector predictor candidatesobtained from the motion vector predictor candidate calculation unit311.

The inverse quantization unit 302 performs inverse quantizationprocessing on the quantization coefficient obtained by variable lengthdecoding processing. The inverse orthogonal transform unit 303transforms an orthogonal transform coefficient obtained by inversequantization processing from a frequency domain into an image domain, togenerate prediction error data. The block memory 305 stores image datagenerated by adding prediction error data and predicted image data, on ablock-by-block basis. The frame memory 306 stores image data on aframe-by-frame basis.

The intra prediction unit 307 generates predicted image data of acurrent block to be decoded by performing intra prediction using imagedata in block units stored in the block memory 305. The inter predictionunit 308 generates predicted image data of a current block to be decodedby performing inter prediction using image data in frame units stored inthe frame memory 306.

If intra prediction decoding is performed on the current block, theswitch 310 outputs the intra-predicted image data generated by the intraprediction unit 307 to the addition unit 304 as predicted image data ofthe current block. In contrast, if inter prediction decoding isperformed on the current block, the switch 310 outputs theinter-predicted image data generated by the inter prediction unit 308 tothe addition unit 304 as predicted image data of the current block.

The motion vector predictor candidate calculation unit 311 derives,using motion vectors of blocks adjacent to the current block, forinstance, and colPic information such as information of a motion vectorof the co-located block stored in the colPic memory 312, for instance,motion vector predictor candidates in the motion vector predictordesignating mode and the number of motion vector predictor candidates byusing the method described below. Further, the motion vector predictorcandidate calculation unit 311 assigns a value of a motion vectorpredictor index to each derived motion vector predictor candidate. Then,the motion vector predictor candidate calculation unit 311 sends themotion vector predictor candidates and the motion vector predictorindices to the inter prediction control unit 309. Further, the motionvector predictor candidate calculation unit 311 sends the number ofcalculated motion vector predictor candidates to the variable lengthdecoding unit 301.

The inter prediction control unit 309 selects, from among the motionvector predictor candidates, a motion vector predictor to be used forinter prediction, based on the decoded motion vector predictor index.Then, the inter prediction control unit 309 calculates a motion vectorof the current block, based on the motion vector predictor and a motionvector difference. Then, the inter prediction control unit 309 causesthe inter prediction unit 308 to generate an inter-predicted image usingthe calculated motion vector. Further, the inter prediction control unit309 transfers colPic information including information of the motionvector of the current block and the like to the colPic memory 312.

Finally, the addition unit 304 generates decoded image data by addingpredicted image data and prediction error data.

FIG. 25 is a flowchart showing processing operation of the movingpicture decoding apparatus according to Embodiment 2.

In step S301, the variable length decoding unit 301 decodes a predictiondirection flag and a reference picture index. Then, the value of theprediction direction X is determined according to the decoded predictiondirection flag, and processing of the following steps S302 to S305 isperformed.

In step S302, the motion vector predictor candidate calculation unit 311derives motion vector predictor candidates from blocks adjacent to thecurrent block and a co-located block using the same method as in stepS102 in FIG. 14 . Further, the motion vector predictor candidatecalculation unit 311 adds a zero candidate, and calculates the motionvector predictor candidate list size.

In step S303, the variable length decoding unit 301 variable-lengthdecodes the motion vector predictor index in a bitstream using thecalculated motion vector predictor candidate list size. In step S304,the inter prediction control unit 309 adds the decoded motion vectordifference to the motion vector predictor candidate indicated by thedecoded motion vector predictor index, to calculate a motion vector.Then, the inter prediction control unit 309 causes the inter predictionunit 308 to generate an inter-predicted image using the calculatedmotion vector.

It should be noted that if the motion vector predictor candidate listsize calculated in step S302 is “1”, it may be estimated that a motionvector predictor index is 0, without being decoded.

In this way, according to the moving picture decoding apparatus 300according to the present embodiment, a bitstream for which codingefficiency has been improved can be appropriately decoded by adding astatic area motion vector predictor to a corresponding one of the motionvector predictor candidate lists. More specifically, if the number ofmotion vector predictor candidates has not reached the maximum number ofmotion vector predictor candidates, the moving picture decodingapparatus 300 can appropriately decode a bitstream for which codingefficiency has been improved by adding a zero candidate having a motionvector whose value is “0” as a motion vector predictor candidate.

It should be noted that in the present embodiment, although the movingpicture decoding apparatus 300 adds a new candidate having a new motionvector predictor as a motion vector predictor candidate if the number ofmotion vector predictor candidates has not reached the number ofavailable predictor candidates, the present invention is not limited tothis. For example, as in Embodiment 1 above, when creating the motionvector predictor candidate lists, the moving picture decoding apparatus300 may set a motion vector (0, 0) whose value is “0” as an initialvalue of all the motion vector predictor candidates on the motion vectorpredictor candidate lists, as shown in (a) in FIG. 21 .

Embodiment 4

The present embodiment is a modification of the moving picture decodingapparatus according to Embodiment 3 above. The following is a specificdescription of a moving picture decoding apparatus according toEmbodiment 4.

FIG. 26 is a block diagram showing a configuration of a moving picturedecoding apparatus 400 according to Embodiment 4. The moving picturedecoding apparatus 400 decodes, on a block-by-block basis, a coded imageincluded in a bitstream generated by the moving picture coding apparatus200 according to Embodiment 2, for example.

As shown in FIG. 26 , the moving picture decoding apparatus 400 includesa motion vector predictor candidate derivation unit 410, a decoding unit420, and a prediction control unit 430.

The motion vector predictor candidate derivation unit 410 corresponds tothe motion vector predictor candidate calculation unit 311 in Embodiment3 above. The motion vector predictor candidate derivation unit 410derives motion vector predictor candidates.

Then, the motion vector predictor candidate derivation unit 410generates motion vector predictor candidate lists in which each derivedmotion vector predictor candidate is associated with an index foridentifying the motion vector predictor candidate (motion vectorpredictor index), for example.

As shown in FIG. 26 , the motion vector predictor candidate derivationunit 410 includes a first derivation unit 411 and a second derivationunit 412.

The first derivation unit 411 derives one or more first motion vectorpredictor candidates as with the first derivation unit 211 in Embodiment2. Specifically, the first derivation unit 411 derives each first motionvector predictor candidate, based on a motion vector used for decoding ablock spatially or temporally adjacent to a current block to be decoded,for example. Then, for example, the first derivation unit 411 registers,into the motion vector predictor candidate lists, the one or more firstmotion vector predictor candidates derived in this way, each inassociation with a motion vector predictor index.

The second derivation unit 412 derives one or more second motion vectorpredictor candidates each having a predetermined vector as a motionvector. Specifically, the second derivation unit 412 derives one or moresecond motion vector predictor candidates in the same manner as that ofthe second derivation unit 212 in Embodiment 2. Then, the secondderivation unit 212 registers, into the motion vector predictorcandidate lists, the one or more second motion vector predictorcandidates derived in this way, each in association with a motion vectorpredictor index, for example.

The predetermined vector may be, for example, a zero vector as inEmbodiment 1 above. This enables the second derivation unit 412 toderive a motion vector predictor candidate having a static area motionvector. Consequently, the moving picture decoding apparatus 400 canappropriately decode a bitstream for which coding efficiency has beenimproved.

The decoding unit 420 obtains an index for identifying a motion vectorpredictor candidate from a bitstream. The decoding unit 420 obtains amotion vector predictor index by decoding a coded motion vectorpredictor index added to the bitstream, using the sum of the number ofderived first motion vector predictor candidates and the number ofderived second motion vector predictor candidates (the number of motionvector predictor candidates), for example.

The prediction control unit 430 selects a motion vector predictor to beused for decoding a current block to be decoded, from among the one ormore first motion vector predictor candidates and the one or more secondmotion vector predictor candidates, based on the obtained index.Specifically, the prediction control unit 430 selects, from the motionvector predictor candidate lists, a motion vector predictor to be usedfor decoding a current block to be decoded.

Next is a description of various operations of the moving picturedecoding apparatus 400 constituted as described above.

FIG. 27 is a flowchart showing processing operation of the movingpicture decoding apparatus 400 according to Embodiment 4.

First, the first derivation unit 411 derives one or more first motionvector predictor candidates (S401). Next, the second derivation unit 412derives one or more second motion vector predictor candidates (S402).Then, the decoding unit 420 obtains a motion vector predictor index froma bitstream (S403).

At last, the prediction control unit 220 selects, from among the one ormore first motion vector predictor candidates and the one or more secondmotion vector predictor candidates, a motion vector predictor to be usedfor decoding a current block to be decoded, based on the obtained index(S404).

As described above, according to the moving picture decoding apparatus400 according to the present embodiment, the one or more second motionvector predictor candidates each having a predetermined vector as amotion vector can be derived. Thus, the moving picture decodingapparatus 400 can derive the one or more second motion vector predictorcandidates each having a static area motion vector or the like, forexample. Specifically, the moving picture decoding apparatus 400 canappropriately decode an image in which a block having predeterminedmotion is efficiently coded, and thus can appropriately decode abitstream for which coding efficiency has been improved.

It should be noted that the moving picture coding apparatus 400 may setthe second motion vector predictor candidate as an initial value of allthe motion vector predictor candidates on the motion vector predictorcandidate lists, as in Embodiment 2 above. In this case, the motionvector predictor candidate derivation unit 410 derives the second motionvector predictor candidate before the first motion vector predictorcandidate. It is also possible to set the second motion vector predictorcandidate as a motion vector predictor candidate by using such a method.

Embodiment 5

The present embodiment describes in detail a method for deriving themotion vector predictor candidate list size, which is different from themethod in Embodiment 1.

In the above motion vector predictor designating mode, the motion vectorpredictor candidate list size to be used when a motion vector predictorindex is coded or decoded is set to the number of motion vectorpredictor candidates. This number of motion vector predictor candidatesis obtained after deleting a non-available predictor candidate or aredundant candidate using reference picture information includinginformation of a co-located block and the like. Thus, if, for instance,there is a difference in the number of motion vector predictorcandidates between a moving picture coding apparatus and a movingpicture decoding apparatus, different bit strings are assigned to motionvector predictor indices in the moving picture coding apparatus and themoving picture decoding apparatus. As a result, the moving picturedecoding apparatus may not be able to decode a bitstream appropriately.

For example, if information of a reference picture which has beenreferenced as a co-located block is lost due to a packet loss or thelike which has occurred on a transmission channel or the like, a motionvector or a reference picture index of the co-located block will belost. Thus, information on a motion vector predictor candidate to begenerated from the co-located block cannot be obtained. In such a case,a non-available predictor candidate and a redundant candidate cannot beappropriately deleted from motion vector predictor candidates at thetime of decoding. As a result, the moving picture decoding apparatuswill not be able to appropriately obtain the motion vector predictorcandidate list size, and will not be able to successfully decode amotion vector predictor index.

In contrast, according to a method for deriving the motion vectorpredictor candidate list size described in the present embodiment, themotion vector predictor candidate list size to be used when a motionvector predictor index is coded or decoded can be calculated by using amethod independent of reference picture information includinginformation of a co-located block and the like. Accordingly, the movingpicture coding apparatus can improve error resistance of a bitstream.

FIG. 28 is a block diagram showing a configuration of a moving picturecoding apparatus 500 according to at Embodiment 3.

As shown in FIG. 28 , the moving picture coding apparatus 500 includes asubtraction unit 501, an orthogonal transform unit 502, a quantizationunit 503, an inverse quantization unit 504, an inverse orthogonaltransform unit 505, an addition unit 506, a block memory 507, a framememory 508, an intra prediction unit 509, an inter prediction unit 510,an inter prediction control unit 511, a picture type determination unit512, a switch 513, a motion vector predictor candidate calculation unit514, a colPic memory 515, and a variable length coding unit 516.

The subtraction unit 501 generates prediction error data by subtracting,for each block, predicted image data from input image data included inan input image sequence. The orthogonal transform unit 502 transformsthe generated prediction error data from an image domain into afrequency domain. The quantization unit 503 performs quantizationprocessing on the prediction error data which has been transformed intothe frequency domain.

The inverse quantization unit 504 performs inverse quantizationprocessing on the prediction error data on which quantization processinghas been performed by the quantization unit 503. The inverse orthogonaltransform unit 505 transforms the prediction error data on which inversequantization processing has been performed, from the frequency domaininto the image domain.

The addition unit 506 generates reconstructed image data by adding, foreach block to be coded, predicted image data and the prediction errordata on which inverse quantization processing has been performed by theinverse orthogonal transform unit 505. The block memory 507 storesreconstructed image data on a block-by-block basis. The frame memory 508stores reconstructed image data on a frame-by-frame basis.

The picture type determination unit 512 determines which of picturetypes, namely, I-picture, B-picture, and P-picture, an input image datais to be coded as. Then, the picture type determination unit 512generates picture type information. The intra prediction unit 509generates intra-predicted image data of a current block to be coded byperforming intra prediction using the reconstructed image data in blockunits stored in the block memory 507. The inter prediction unit 510generates inter-predicted image data of a current block to be coded byperforming inter prediction using the reconstructed image data in frameunits stored in the frame memory 508, and a motion vector derived bymotion detection and the like.

The switch 513 outputs the intra-predicted image data generated by theintra prediction unit 509 to the subtraction unit 501 and the additionunit 506 as predicted image data of the current block, if intraprediction coding is performed on the current block. On the other hand,the switch 513 outputs the inter-predicted image data generated by theinter prediction unit 510 to the subtraction unit 501 and the additionunit 506 as predicted image data of the current block if the interprediction coding is performed on the current block.

The motion vector predictor candidate calculation unit 514 derivesmotion vector predictor candidates in the motion vector predictordesignating mode, using motion vectors of blocks adjacent to the currentblock and the like and colPic information such as information of amotion vector of a co-located block stored in the colPic memory 515.Then, the motion vector predictor candidate calculation unit 514calculates the number of available predictor candidates using the methoddescribed below. Further, the motion vector predictor candidatecalculation unit 514 assigns the values of the motion vector predictorindex to the derived motion vector predictor candidates. Then, themotion vector predictor candidate calculation unit 514 sends the motionvector predictor candidates and the motion vector predictor indices tothe inter prediction control unit 511. The motion vector predictorcandidate calculation unit 514 transmits the number of calculatedavailable predictor candidates to the variable length coding unit 516.

The inter prediction control unit 511 controls the inter prediction unit510 so as to cause the inter prediction unit 110 to perform interprediction coding, using the inter-predicted image generated using amotion vector derived by motion detection. Further, the inter predictioncontrol unit 511 selects, using the method described below, a motionvector predictor candidate most suitable for coding a motion vector usedfor inter prediction coding. Then, the inter prediction control unit 511sends a motion vector predictor index corresponding to the selectedmotion vector predictor candidate, and prediction error information(motion vector difference) to the variable length coding unit 516.Furthermore, the inter prediction control unit 511 transfers colPicinformation including information of a motion vector of the currentblock and the like to the colPic memory 515.

The variable length coding unit 516 performs variable length codingprocessing on prediction error data on which quantization processing hasbeen performed, a prediction direction flag, picture type information,and a motion vector difference, thereby generating a bitstream. Further,the variable length coding unit 516 sets the motion vector predictorcandidate list size to the number of available predictor candidates.Then, the variable length coding unit 516 variable-length codes themotion vector predictor index used for coding a motion vector byassigning, thereto, a bit string according to the motion vectorpredictor candidate list size.

FIG. 29 is a flowchart showing processing operation of the movingpicture coding apparatus according to Embodiment 1.

In step S501, the inter prediction control unit 511 determines aprediction direction, a reference picture index, and a motion vector ofa current block to be coded by motion detection. Here, in motiondetection, a difference value indicating a difference between a currentblock to be coded in a picture to be coded and a block in a referencepicture is calculated, and a block in the reference picture with whichthe difference value is smallest is determined as a reference block.Then, a motion vector is obtained based on the position of a currentblock to be coded and the position of a reference block position usingthe method for obtaining a motion vector, for instance. Further, theinter prediction control unit 511 performs motion detection on each ofreference pictures in the prediction directions 0 and 1, and determineswhether to select the prediction direction 0, the prediction direction 1or bidirectional prediction using, for example, the following expressionfor an R-D optimization model, or the like.

Cost=D+λ×R   (Expression 3)

In Expression 3, D denotes coding distortion, and for instance, a sum ofabsolute differences are used therefor each of which is an absolutedifference between a pixel value obtained by coding and decoding acurrent block using a predicted image generated using a certain motionvector and an original pixel value of the current block. R denotes agenerated code amount, and a code amount necessary to code a motionvector used for generating a predicted image is used therefor. Further,λ denotes a Lagrange undetermined multiplier.

In step S502, the motion vector predictor candidate calculation unit 514derives motion vector predictor candidates from blocks adjacent to thecurrent block and a co-located block thereof. Further, the motion vectorpredictor candidate calculation unit 514 calculates the motion vectorpredictor candidate list size according to the method described below.

For example, in the case as shown in FIG. 3 , the motion vectorpredictor candidate calculation unit 514 selects motion vectors whichadjacent blocks A, B, C, and D have, as motion vector predictorcandidates of the current block. Furthermore, the motion vectorpredictor candidate calculation unit 514 calculates a motion vector, forinstance, which is calculated using a temporal prediction mode from amotion vector of the co-located block, as a motion vector predictorcandidate.

The motion vector predictor candidate calculation unit 514 assignsmotion vector predictor indices to the motion vector predictorcandidates in the prediction directions 0 and 1, as shown in (a) in FIG.30 and (a) in FIG. 31 . Then, the motion vector predictor candidatecalculation unit 514 calculates motion vector predictor candidate listsas shown in (b) in FIG. 30 and (b) in FIG. 31 , and the sizes of themotion vector predictor candidate lists by deleting a non-availablepredictor candidate and a redundant candidate and adding a new candidateaddition, using the method described below.

The smaller a value of a motion vector predictor index is, the shortercode is assigned to the motion vector predictor index. Specifically, ifthe value of a motion vector predictor index is small, the amount ofinformation necessary for the motion vector predictor index is small. Onthe other hand, if the value of a motion vector predictor index islarge, the amount of information necessary for the motion vectorpredictor index is large. Thus, coding efficiency is increased byassigning a motion vector predictor index having a small value to amotion vector predictor candidate having a high possibility of becominga motion vector predictor with high precision.

In view of this, the motion vector predictor candidate calculation unit514 may measure, for each motion vector predictor candidate, the numberof times at which the motion vector predictor candidate has beenselected as a motion vector predictor, and assign a motion vectorpredictor index having a small value to a block from which a motionvector predictor candidate whose number of times at which the candidatehas been selected is large is obtained, for example. Specifically, it ispossible to consider identifying a motion vector predictor selected inan adjacent block, and in coding a current block, assigning a motionvector predictor index having a small value to the identified motionvector predictor candidate.

It should be noted that if a motion vector predictor candidate does nothave information of a motion vector and the like (if the candidate is ablock coded by intra prediction, if the candidate is a block located,for instance, outside a boundary of a picture or a slice, if thecandidate is a block which is not coded yet, or the like), the candidatecannot be utilized for coding.

In the present embodiment, a candidate that cannot be utilized as amotion vector predictor candidate is referred to as a non-availablepredictor candidate. A candidate that can be utilized as a motion vectorpredictor candidate is referred to as an available predictor candidate.Further, among a plurality of motion vector predictor candidates, acandidate whose value is the same as any one of the other motion vectorpredictors is referred to as a redundant candidate.

In the case of FIG. 3 , adjacent block C is a block coded by intraprediction, and thus is assumed to be a non-available predictorcandidate. Further, motion vector predictor sMvL0_D in the predictiondirection 0 generated from adjacent block D has the same value as thevalue of motion vector predictor MvL0_A in the prediction direction 0generated from adjacent block A, and thus is assumed to be a redundantcandidate.

In step S503, the inter prediction control unit 511 determines a valueof a motion vector predictor index to be used for coding a motion vectorin the prediction direction X by using the method described below.

In step S504, the variable length coding unit 516 variable length-codesmotion vector predictor indices of motion vector predictor candidates tobe used for coding motion vectors in the prediction direction X byassigning thereto bit strings according to the motion vector predictorcandidate list size as shown in FIG. 6 .

In the present embodiment, as shown in (a) in FIG. 30 and (a) in FIG. 31, “0” is assigned as a value of a motion vector predictor indexcorresponding to adjacent block A. “1” is assigned as a value of amotion vector predictor index corresponding to adjacent block B. “2” isassigned as a value of a motion vector predictor index corresponding toa co-located block. “3” is assigned as a value of a motion vectorpredictor index corresponding to adjacent block C. “4” is assigned as avalue of a motion vector predictor index corresponding to adjacent blockD.

It should be noted that the way to assign motion vector predictorindices is not necessarily limited to this example. For example, if anew candidate is added using the method described in Embodiment 1 or themethod described below, the variable length coding unit 516 may assign asmall value to a motion vector predictor candidate which is not newlyadded, and a large value to the new candidate. Specifically, thevariable length coding unit 516 may preferentially assign a motionvector predictor index having a small value to a motion vector predictorcandidate which is not newly added.

Further, motion vector predictor candidates are not necessarily limitedto be at the positions of adjacent blocks A, B, C, and D. For example, avector of an adjacent block located on bottom-left adjacent block D, forinstance, may be used as a motion vector predictor candidate. Further,vectors of all the adjacent blocks do not necessarily need to be used asmotion vector predictor candidates. For example, vectors of onlyadjacent blocks A and B may be used as motion vector predictorcandidates. Alternatively, adjacent blocks may be sequentially scannedby using, for instance, adjacent block A if adjacent block D is anon-available predictor candidate.

Further, in the present embodiment, although the variable length codingunit 516 adds a motion vector predictor index to a bitstream in stepS504 in FIG. 29 , a motion vector predictor index does not necessarilyneed to be added to a bitstream. For example, if the motion vectorpredictor candidate list size is 1, the variable length coding unit 516may not add a motion vector predictor index to a bitstream. Accordingly,the amount of information can be reduced by that of the motion vectorpredictor index.

FIG. 32 is a flowchart showing detailed processing of step S502 in FIG.29 . Specifically, FIG. 32 shows a method for calculating motion vectorpredictor candidates and the motion vector predictor candidate listsize. The following is a description of FIG. 32 .

In step S511, the motion vector predictor candidate calculation unit 514determines, using the method described below, whether a prediction blockcandidate [N] is an available predictor candidate. Then, the motionvector predictor candidate calculation unit 514 updates the number ofavailable predictor candidates in accordance with the determinationresult.

Here, N is an index value for denoting each prediction block candidate.In the present embodiment, N is one of the values from 0 to 4.Specifically, adjacent block A in FIG. 3 is assigned to a predictionblock candidate [0]. Adjacent block B in FIG. 3 is assigned to aprediction block candidate [1]. A co-located block is assigned to aprediction block candidate [2]. Adjacent block C in FIG. 3 is assignedto a prediction block candidate [3]. Adjacent block D in FIG. 3 isassigned to a prediction block candidate [4].

In step S512, the motion vector predictor candidate calculation unit 514derives a motion vector predictor candidate in the prediction directionX from the prediction block candidate [N] using Expressions 1 and 2above, and adds the derived candidate to a corresponding one of themotion vector predictor candidate lists.

In step S513, the motion vector predictor candidate calculation unit 514searches for and deletes a non-available predictor candidate and aredundant candidate from the motion vector predictor candidate lists, asshown in FIGS. 30 and 31 .

In step S514, the motion vector predictor candidate calculation unit 514adds a new candidate to a corresponding one of the motion vectorpredictor candidate lists, using the method of described in Embodiment 1or the method described below. Here, when a new candidate is added, themotion vector predictor candidate calculation unit 514 may reassignvalues of motion vector predictor indices so as to preferentially assigna small motion vector predictor index to a motion vector predictorcandidate which is not newly added. Specifically, the motion vectorpredictor candidate calculation unit 514 may reassign values of motionvector predictor indices so as to assign a motion vector predictor indexhaving a large value to the new candidate. Accordingly, the amount ofcoding motion vector predictor indices can be reduced.

In step S515, the motion vector predictor candidate calculation unit 514sets the motion vector predictor candidate list size to the number ofavailable predictor candidates calculated in step S511. In the examplesof FIGS. 30 and 31 , by using the method described below, “4” iscalculated as the number of available predictor candidates in theprediction direction 0, and the motion vector predictor candidate listsize for the prediction direction 0 is set to “4”. Further, “4” iscalculated as the number of available predictor candidates in theprediction direction 1, and the motion vector predictor candidate listsize for the prediction direction 1 is set to “4”.

It should be noted that a new candidate in step S514 is a zero candidateadded using the method described in Embodiment 1, or a candidate newlyadded to the motion vector predictor candidates using the methoddescribed below if the number of motion vector predictor candidates hasnot reached the number of available predictor candidates. For example, anew candidate may be a motion vector predictor generated from anadjacent block located on bottom-left adjacent block D in FIG. 3 . A newcandidate may be a motion vector predictor generated from blockscorresponding to blocks A, B, C, and D adjacent a co-located block, forexample. Further, a new candidate may be a motion vector predictorcalculated from a total of motion vectors in the entire picture plane ora certain area of a reference picture, for example. In this way, codingefficiency can be improved by the motion vector predictor candidatecalculation unit 514 adding a new motion vector predictor as a newcandidate if the number of motion vector predictor candidates has notreached the number of available predictor candidates.

FIG. 33 is a flowchart showing detailed processing of step S511 in FIG.32 . Specifically, FIG. 33 shows a method for determining whether theprediction block candidate [N] is an available predictor candidate, andupdating the number of available predictor candidates. The following isa description of FIG. 33 .

In step S521, the motion vector predictor candidate calculation unit 514determines whether a prediction block candidate [N] is (1)intra-predicted, (2) located outside a boundary of a slice or a picturewhich includes a current block to be coded, or (3) is not coded yet.

Here, if the determination result in step S521 is true (Yes in S521),the motion vector predictor candidate calculation unit 514 sets theprediction block candidate [N] as a non-available predictor candidate instep S522. On the other hand, if the determination result in step S521is false (No in S521), the motion vector predictor candidate calculationunit 514 sets the prediction block candidate [N] as an availablepredictor candidate in step S523.

In step S524, the motion vector predictor candidate calculation unit 514determines whether the prediction block candidate [N] is an availablepredictor candidate or a co-located block candidate. Here, if thedetermination result in step S524 is true (Yes in S524), the motionvector predictor candidate calculation unit 514 adds 1 to the number ofavailable predictor candidates, and updates the number of motion vectorpredictor candidates in step S5. On the other hand, if the determinationresult in step S524 is false (No in S524), the motion vector predictorcandidate calculation unit 514 does not update the number of availablepredictor candidates.

As described above, if a prediction block candidate is a co-locatedblock, the motion vector predictor candidate calculation unit 514 adds 1to the number of available predictor candidates, irrespective of whetherthe co-located block is an available predictor candidate or anon-available predictor candidate. Accordingly, even if information of aco-located block is lost due to packet loss or the like, there is nodifference in the number of available predictor candidates between themoving picture coding apparatus and the moving picture decodingapparatus.

The motion vector predictor candidate list size is set to the number ofavailable predictor candidates in step S515 in FIG. 32 . Furthermore, inS504 in FIG. 29 , the motion vector predictor candidate list size isused for variable-length coding motion vector predictor indices.Accordingly, even if reference picture information including informationof a co-located block and the like is lost, the moving picture codingapparatus 500 can generate a bitstream from which a motion vectorpredictor index can be successfully decoded.

FIG. 34 is a flowchart showing detailed processing of step S514 in FIG.32 . Specifically, FIG. 34 shows a method for adding a new candidate.The following is a description of FIG. 34 .

In step S531, the motion vector predictor candidate calculation unit 514determines whether the number of motion vector predictor candidates issmaller than the number of available predictor candidates. Specifically,the motion vector predictor candidate calculation unit 514 determineswhether the number of motion vector predictor candidates has not reachedthe number of available predictor candidates.

Here, if the determination result in step S531 is true (Yes in S531),the motion vector predictor candidate calculation unit 514 determines instep S532 whether there is a new candidate which can be added to acorresponding one of the motion vector predictor candidate lists as amotion vector predictor candidate. Here, if the determination result instep S532 is true (Yes in S532), the motion vector predictor candidatecalculation unit 514 assigns a value of a motion vector predictor indexto the new candidate, and adds the new candidate to a corresponding oneof the motion vector predictor candidate lists in step S533.Furthermore, in step S534, the motion vector predictor candidatecalculation unit 514 adds 1 to the number of motion vector predictorcandidates.

On the other hand, if the determination result in step S531 or step S532is false (No in S531 or S532), new candidate adding processing ends.Specifically, if the number of motion vector predictor candidates hasreached the number of available predictor candidates, or if there is nonew candidate, new candidate adding processing ends.

FIG. 35 is a flowchart showing detailed processing of step S503 in FIG.29 . Specifically, FIG. 35 shows processing regarding selection of amotion vector predictor candidate. The following is a description ofFIG. 35 .

In step S541, as initialization, the inter prediction control unit 511sets motion vector predictor candidate index mvp_idx to 0, and sets thesmallest motion vector difference to the maximum value.

In step S542, the inter prediction control unit 511 determines whetherthe value of motion vector predictor candidate index mvp_idx is smallerthan the number of motion vector predictor candidates. Specifically, theinter prediction control unit 511 determines whether motion vectordifferences of all the motion vector predictor candidates have beencalculated.

Here, if there still remains a motion vector predictor candidate forwhich calculation has not been performed (Yes in S542), the interprediction control unit 511 calculates a motion vector difference bysubtracting a motion vector predictor candidate from a vector obtainedas a result of motion detection (motion detection resultant vector) instep S543.

In step S544, the inter prediction control unit 511 determines whetherthe motion vector difference obtained in step S543 has a value smallerthan the smallest motion vector difference.

Here, if the determination result in step S544 is true (Yes in S544),the inter prediction control unit 511 updates the smallest motion vectordifference and the value of a motion vector predictor index in stepS545. On the other hand, if the determination result in step S544 isfalse (No in S544), the inter prediction control unit 511 does notupdate the smallest motion vector difference and the value of a motionvector predictor index.

In step S546, the inter prediction control unit 511 updates a motionvector predictor candidate index by incrementing by +1, and returningback to step S542, the inter prediction control unit 111 determineswhether a next motion vector predictor candidate is present.

On the other hand, if it is determined in step S2 that a motion vectordifference has been calculated for all the motion vector predictorcandidates (No in S542), the inter prediction control unit 511 fixes, instep S547, the smallest motion vector difference and the motion vectorpredictor index which are set at last.

In this way, according to the moving picture coding apparatus 500according to the present embodiment, the motion vector predictorcandidate list size to be used when a motion vector predictor index iscoded or decoded can be calculated using a method independent ofreference picture information including information of a co-locatedblock and the like. Accordingly, the moving picture coding apparatus 500can improve error resistance.

More specifically, the moving picture coding apparatus 500 according tothe present embodiment adds 1 to the number of available predictorcandidates if a prediction block candidate is a co-located block,irrespective of whether the co-located block is an available predictorcandidate. Then, the moving picture coding apparatus 500 determines abit string to be assigned to a motion vector predictor index using thenumber of available predictor candidates calculated in this way.Accordingly, the moving picture coding apparatus 500 can generate abitstream from which a motion vector predictor index can be successfullydecoded even if reference picture information including information of aco-located block is lost.

Further, the moving picture coding apparatus 500 according to thepresent embodiment can improve coding efficiency by adding a newcandidate having a new motion vector predictor as a motion vectorpredictor candidate if the number of motion vector predictor candidateshas not reached the number of available predictor candidates.

It should be noted that in the present embodiment, the moving picturecoding apparatus 500 determines a bit string to be assigned to a motionvector predictor index using the number of available predictorcandidates calculated by always adding 1 if a prediction block candidateis a co-located block irrespective of whether the co-located block is anavailable predictor candidate, the present invention is not limited tothis. For example, the moving picture coding apparatus 500 may determinea bit string to be assigned to a motion vector predictor index, usingthe number of available predictor candidates calculated by always adding1 also in the case of a prediction block candidate other than theco-located block in step S524 in FIG. 33 . Specifically, the movingpicture coding apparatus 500 may assign a bit string to a motion vectorpredictor index using the motion vector predictor candidate list sizefixed to the maximum value N of the number of motion vector predictorcandidates. In other words, the moving picture coding apparatus mayassume that all prediction block candidates are available predictorcandidates, fix the motion vector predictor candidate list size to themaximum value N of the number of motion vector predictor candidates, andcode motion vector predictor indices.

For example, in the present embodiment, the maximum value N of thenumber of motion vector predictor candidates is 5 (adjacent block A,adjacent block B, co-located block, adjacent block C, adjacent block D),and thus the moving picture coding apparatus 500 may always set themotion vector predictor candidate list size to 5, and code motion vectorpredictor indices. Further, for example, if the maximum value N of thenumber of motion vector predictor candidates is 4 (adjacent block A,adjacent block B, adjacent block C, adjacent block D), the movingpicture coding apparatus 500 may always set the motion vector predictorcandidate list size to 4, and code motion vector predictor indices.

In this way, the moving picture coding apparatus 500 may determine themotion vector predictor candidate list size according to the maximumvalue of the number of motion vector predictor candidates. Accordingly,it is possible to generate a bitstream from which the variable lengthdecoding unit 516 of the moving picture decoding apparatus 500 candecode a motion vector predictor index in a bitstream without referringto information of adjacent blocks or a co-located block, which resultsin a reduction of the amount of processing to be performed by thevariable length decoding unit 516.

Although the present embodiment describes an example in which the motionvector predictor designating mode is used in which motion vectorpredictor candidates are generated from blocks adjacent to a currentblock to be coded, and a motion vector of the current block is coded,the present embodiment is not necessarily limited to this. For example,a direct mode or a skip mode may be used. In the direct mode or the skipmode, a motion vector difference may not be added to a bitstream byselecting a motion vector predictor from among the motion vectorpredictor candidates created as shown in (b) in FIG. 30 and (b) in FIG.31 , and directly generating a predicted image using the selected motionvector predictor as a motion vector.

Embodiment 6

The present embodiment is a modification of the moving picture codingapparatus according to Embodiment 5 above. The following is a specificdescription of a moving picture coding apparatus according to Embodiment6.

FIG. 36 is a block diagram showing a configuration of a moving picturecoding apparatus 600 according to at Embodiment 6. The moving picturecoding apparatus 600 generates a bitstream by coding an image on ablock-by-block basis. The moving picture coding apparatus 600 includes amotion vector predictor candidate derivation unit 610, a predictioncontrol unit 620, and a coding unit 630.

The motion vector predictor candidate derivation unit 610 corresponds tothe motion vector predictor candidate calculation unit 514 in Embodiment5 above. The motion vector predictor candidate derivation unit 610derives motion vector predictor candidates. Then, the motion vectorpredictor candidate derivation unit 610 generates motion vectorpredictor candidate lists in which each derived motion vector predictorcandidate is associated with an index for identifying the motion vectorpredictor candidate, for example.

As shown in FIG. 36 , the motion vector predictor candidate derivationunit 610 includes a maximum number determination unit 611, a firstderivation unit 612, an identification unit 613, a determination unit614, and a second derivation unit 615.

The maximum number determination unit 611 determines the maximum numberof motion vector predictor candidates. Specifically, the maximum numberdetermination unit 611 determines the maximum value N of the number ofprediction block candidates.

For example, the maximum number determination unit 611 determines themaximum number of motion vector predictor candidates, based on featuresof an input image sequence (sequence, pictures, slices, or blocks).Further, for example, the maximum number determination unit 611 maydetermine a predetermined number as the maximum number of motion vectorpredictor candidates.

The first derivation unit 612 derives each first motion vector predictorcandidate, based on a motion vector used for coding a block spatially ortemporally adjacent to a current block to be coded. Here, the firstderivation unit 612 derives one or more first motion vector predictorcandidates such that the number of first motion vector predictorcandidates does not exceed the maximum number. Then, for example, thefirst derivation unit 612 registers, into the motion vector predictorcandidate lists, the one or more first motion vector predictorcandidates derived in this way, each in association with a motion vectorpredictor index.

It should be noted that, for example, the first derivation unit 612 mayderive, as the first motion vector predictor candidate, a motion vectorused for coding a block that is a block spatially adjacent to a currentblock to be coded, and is not a block which is a non-available predictorcandidate. A block which is a non-available predictor candidate is ablock coded by intra prediction, a block located outside a boundary of aslice or a picture which includes a current block to be coded, or ablock which is not coded yet. Accordingly, the first motion vectorpredictor candidate can be derived from a block suitable for obtaining amotion vector predictor candidate.

The identification unit 613 identifies a first motion vector predictorcandidate (redundant candidate) having the same motion vector as that ofany other first motion vector predictor candidate, if a plurality of thefirst motion vector predictor candidates are derived. Then, theidentification unit 613 deletes the identified redundant candidate froma corresponding one of the motion vector predictor candidate lists.

The determination unit 614 determines whether the number of first motionvector predictor candidates is smaller than the determined maximumnumber. Here, the determination unit 614 determines whether the numberof first motion vector predictor candidates excluding the identifiedredundant first motion vector predictor candidate is smaller than thedetermined maximum number.

If it is determined that the number of first motion vector predictorcandidates is smaller than the determined maximum number, the secondderivation unit 615 derives one or more second motion vector predictorcandidates each having a predetermined vector as a motion vector.Specifically, the second derivation unit 615 derives the second motionvector predictor candidates such that the sum of the number of firstmotion vector predictor candidates and the number of second motionvector predictor candidates does not exceed the maximum number. Here,the second derivation unit 615 derives the second motion vectorpredictor candidates such that the sum of the number of first motionvector predictor candidates excluding a redundant candidate and thenumber of second motion vector predictor candidates does not exceed themaximum number.

The predetermined vector may be a zero vector as in the above Embodiment1 above, for example. It should be noted that the predetermined vectordoes not necessarily need to be a zero vector.

Then, the second derivation unit 615 registers, into the motion vectorpredictor candidate lists, the one or more second motion vectorpredictor candidates derived in this way, each in association with amotion vector predictor index, for example. At this time, the secondderivation unit 615 may register the second motion vector predictorcandidates into a corresponding one of the motion vector predictorcandidate lists, such that a motion vector predictor index having avalue smaller than that for the second motion vector predictorcandidates is assigned to each first motion vector predictor candidate.Accordingly, if there is a high possibility that the first motion vectorpredictor candidate will be selected as a motion vector predictorcandidate to be used for coding rather than the second motion vectorpredictor candidates, the moving picture coding apparatus 600 can reducethe code amount, and improve coding efficiency.

It should be noted that the second derivation unit 615 does notnecessarily need to derive the one or more second motion vectorpredictor candidates such that the sum of the number of first motionvector predictor candidates and the number of second motion vectorpredictor candidates will be the same as the determined maximum number.If the sum of the number of first motion vector predictor candidates andthe number of second motion vector predictor candidates is smaller thanthe determined maximum number, there may be a value of a motion vectorpredictor index which is not associated with a motion vector predictorcandidate, for example.

The prediction control unit 620 selects a motion vector predictor to beused for coding a current block to be coded, from among the one ore morefirst motion vector predictor candidates and the one ore more secondmotion vector predictor candidates. Specifically, the prediction controlunit 620 selects, from the motion vector predictor candidate lists, amotion vector predictor to be used for coding the current block.

The coding unit 630 codes an index (motion vector predictor index) foridentifying the selected motion vector predictor candidate, using thedetermined maximum number. Specifically, the coding unit 630variable-length codes a bit string assigned to the index value of theselected motion vector predictor candidate, as shown in FIG. 6 .Furthermore, the coding unit 630 adds the coded index to a bitstream.

Here, the coding unit 630 may further add information indicating themaximum number determined by the maximum number determination unit 611to the bitstream. Specifically, the coding unit 630 may also writeinformation indicating the maximum number, for example, into a sliceheader or the like. Accordingly, the maximum number can be changed in asuitable unit, which can improve coding efficiency.

It should be noted that the coding unit 630 does not necessarily need toadd information indicating the maximum number to a bitstream. Forexample, if the maximum number is previously determined according to astandard, or if the maximum number is the same as a default value, thecoding unit 630 does not need to add information indicating the maximumnumber to a bitstream.

Next is a description of various operations of the moving picture codingapparatus 600 constituted as described above.

FIG. 37 is a flowchart showing processing operation of the movingpicture coding apparatus 600 according to Embodiment 6.

First, the maximum number determination unit 611 determines the maximumnumber of motion vector predictor candidates (S601). The firstderivation unit 612 derives one or more first motion vector predictorcandidates (S602). The identification unit 613 identifies a first motionvector predictor candidate (redundant candidate) having the same motionvector as that of any other first motion vector predictor candidate, ifa plurality of the first motion vector predictor candidates are derived(S603).

The determination unit 614 determines whether the number of first motionvector predictor candidates excluding a redundant candidate is smallerthan the determined maximum number (S604). Here, if it is determinedthat the number of first motion vector predictor candidates excluding aredundant candidate is smaller than the determined maximum number (Yesin S604), the second derivation unit 615 derives one ore more secondmotion vector predictor candidates each having a predetermined vector asa motion vector (S605). On the other hand, if it is not determined thatthe number of first motion vector predictor candidates excluding aredundant candidate is smaller than the determined maximum number (No inS604), the second derivation unit 615 does not derive a second motionvector predictor candidate. These steps S604 and S605 correspond to stepS514 in Embodiment 5.

The prediction control unit 620 selects a motion vector predictor to beused for coding a current block to be coded from among the one or morefirst motion vector predictor candidates and the one or more secondmotion vector predictor candidate (S606). For example, the predictioncontrol unit 620 selects a motion vector predictor with which a motionvector difference is the smallest from the motion vector predictorcandidate lists, as in Embodiment 1.

The coding unit 630 codes an index for identifying the selected motionvector predictor candidate using the determined maximum number (S607).Furthermore, the coding unit 630 adds the coded index to a bitstream.

As described above, according to the moving picture coding apparatus 600according to the present embodiment, the one or more second motionvector predictor candidates each having a predetermined vector as amotion vector can be derived. Thus, the moving picture coding apparatus600 can derive a motion vector predictor candidate which has, forexample, a static area motion vector or the like, as the second motionvector predictor candidate. Specifically, the moving picture codingapparatus 600 can efficiently code a current block to be coded which haspredetermined motion, and can improve coding efficiency.

Furthermore, according to the moving picture coding apparatus 600according to the present embodiment, an index for identifying a motionvector predictor candidate can be coded using the determined maximumnumber. Specifically, an index can be coded without depending on thenumber of motion vector predictor candidates actually derived. Thus,even if information necessary for deriving a motion vector predictorcandidate (for example, information of a co-located block and the like)is lost, a decoding apparatus can decode an index, and error resistancecan be improved. Further, the decoding apparatus can decode an index,without depending on the number of motion vector predictor candidatesactually derived. Specifically, the decoding apparatus can decode theindex, without waiting for derivation of a motion vector predictorcandidate. In other words, it is possible to generate a bitstream forwhich deriving a motion vector predictor candidate and decoding an indexcan be performed in parallel.

Furthermore, according to the moving picture coding apparatus 600according to the present embodiment, one or more second motion vectorpredictor candidates can be derived if it is determined that the numberof first motion vector predictor candidates is smaller than the maximumnumber. Thus, it is possible to increase the number of motion vectorpredictor candidates in a range which does not exceed the maximumnumber, and improve coding efficiency.

In addition, according to the moving picture coding apparatus 600according to the present embodiment, one or more second motion vectorpredictor candidates can be derived according to the number of firstmotion vector predictor candidates excluding the redundant first motionvector predictor candidate. As a result, the number of second motionvector predictor candidates can be increased, and the types of motionvectors selectable as motion vector predictor candidates can beincreased. Thus, it is possible to further improve coding efficiency.

It should be noted that in the present embodiment, although the movingpicture coding apparatus 600 includes the identification unit 613, themoving picture coding apparatus 600 does not necessarily need to includethe identification unit 613. Specifically, step S603 does notnecessarily need to be included in the flowchart shown in FIG. 37 . Evenin such a case, the moving picture coding apparatus 600 can code anindex for identifying a motion vector predictor candidate using thedetermined maximum number, and thus error resistance can be improved.

Further, although in the present embodiment, the first derivation unit612 derives the first motion vector predictor candidates, and thereafterthe identification unit 613 identifies a redundant candidate as shown inFIG. 37 , the processing does not necessarily need to be performedsequentially in this way. For example, in the process of deriving thefirst motion vector predictor candidates, the first derivation unit 612may identify a redundant candidate, and derive the first motion vectorpredictor candidates such that the identified redundant candidate is notincluded in the first motion vector predictor candidates. Specifically,the first derivation unit 612 may derive a motion vector predictorcandidate which is not the same as a motion vector of any first motionvector predictor candidate which has already been derived, as the firstmotion vector predictor candidate. More specifically, for example, whena motion vector predictor candidate based on a left adjacent block isalready derived as the first motion vector predictor candidate, if amotion vector predictor candidate based on an upper adjacent block isnot the same as the motion vector predictor candidate based on the leftadjacent block, the first derivation unit 612 may derive the motionvector predictor candidate based on the upper adjacent block as thefirst motion vector predictor candidate. This allows the firstderivation unit 612 to exclude, from the first motion vector predictorcandidates, a motion vector predictor candidate having the same motionvector as a motion vector of any of the first motion vector predictorcandidates which have already been derived. As a result, the movingpicture coding apparatus 600 can increase the number of second motionvector predictor candidates, and increase the type of motion vectorsselectable as motion vector predictor candidates. Thus, it is possibleto further improve coding efficiency.

Embodiment 7

The present embodiment describes in detail a method for deriving themotion vector predictor candidate list size different from the method inEmbodiment 2.

FIG. 38 is a block diagram showing a configuration of a moving picturedecoding apparatus 700 according to Embodiment 4.

As shown in FIG. 38 , the moving picture decoding apparatus 700 includesa variable length decoding unit 701, an inverse quantization unit 702,an inverse orthogonal transform unit 703, an addition unit 704, a blockmemory 705, a frame memory 706, an intra prediction unit 707, an interprediction unit 708, an inter prediction control unit 709, a switch 710,a motion vector predictor candidate calculation unit 711, and a colPicmemory 712.

The variable length decoding unit 701 performs variable length decodingprocessing on an input bitstream, and generates picture typeinformation, a prediction direction flag, a quantization coefficient,and a motion vector difference. Further, the variable length decodingunit 701 performs variable length decoding processing on motion vectorpredictor indices using the number of available predictor candidatesdescribed below.

The inverse quantization unit 702 performs inverse quantizationprocessing on the quantization coefficient obtained by variable lengthdecoding processing. The inverse orthogonal transform unit 703transforms an orthogonal transform coefficient obtained by inversequantization processing from a frequency domain into an image domain, togenerate prediction error data. The block memory 705 stores decodedimage data generated by adding prediction error data and predicted imagedata, on a block-by-block basis. The frame memory 706 stores image dataon a frame-by-frame basis.

The intra prediction unit 707 generates predicted image data of acurrent block to be decoded by performing intra prediction using imagedata in block units stored in the block memory 705. The inter predictionunit 708 generates predicted image data of a current block to be decodedby performing inter prediction using image data in frame units stored inthe frame memory 706.

If intra prediction decoding is performed on the current block, theswitch 710 outputs the intra-predicted image data generated by the intraprediction unit 707 to the addition unit 704 as predicted image data ofthe current block. In contrast, if inter prediction decoding isperformed on the current block, the switch 710 outputs theinter-predicted image data generated by the inter prediction unit 708 tothe addition unit 704 as predicted image data of the current block.

Using, for instance, motion vectors of blocks adjacent to a currentblock to be decoded and colPic information such as information of amotion vector of a co-located block stored in the colPic memory 712, themotion vector predictor candidate calculation unit 711 derives motionvector predictor candidates in the motion vector predictor designatingmode by using the method described below. Further, the motion vectorpredictor candidate calculation unit 711 assigns a value of a motionvector predictor index to each derived motion vector predictorcandidate. Then, the motion vector predictor candidate calculation unit711 sends the motion vector predictor candidates and the motion vectorpredictor indices to the inter prediction control unit 709.

The inter prediction control unit 709 selects, from among the motionvector predictor candidates, a motion vector predictor to be used forinter prediction, based on the decoded motion vector predictor index.Then, the inter prediction control unit 709 calculates a motion vectorof the current block, based on the motion vector predictor and a motionvector difference. Then, the inter prediction control unit 709 causesthe inter prediction unit 708 to generate an inter-predicted image usingthe calculated motion vector. Further, the inter prediction control unit709 transfers colPic information including information of the motionvector of the current block and the like to the colPic memory 712.

Finally, the addition unit 704 generates decoded image data by addingpredicted image data and prediction error data.

FIG. 39 is a flowchart showing processing operation of the movingpicture decoding apparatus according to Embodiment 2.

In step S701, the variable length decoding unit 701 decodes a predictiondirection flag and a reference picture index. Then, the value of theprediction direction X is determined according to the decoded predictiondirection flag, and processing of the following steps S702 to S705 isperformed.

In step S702, the motion vector predictor candidate calculation unit 711calculates the number of available predictor candidate, using themethods described in Embodiments 1 and 2 or the method described below.Then, the motion vector predictor candidate calculation unit 711 setsthe motion vector predictor candidate list size to the calculated numberof available predictor candidates.

In step S703, the variable length decoding unit 701 variable-lengthdecodes the motion vector predictor index in a bitstream using thecalculated motion vector predictor candidate list size. In step S704,the motion vector predictor candidate calculation unit 711 generatesmotion vector predictor candidates from blocks adjacent to the currentblock and a co-located block using the method described below. In stepS705, the inter prediction control unit 709 adds the decoded motionvector difference to the motion vector predictor candidate indicated bythe decoded motion vector predictor index, to calculate a motion vector.Then, the inter prediction control unit 709 causes the inter predictionunit 708 to generate an inter-predicted image using the calculatedmotion vector.

It should be noted that if the motion vector predictor candidate listsize calculated in step S702 is “1”, it may be estimated that a motionvector predictor index is 0, without being decoded.

FIG. 40 is a flowchart showing detailed processing of step S702 in FIG.39 . Specifically, FIG. 40 shows a method for determining whether aprediction block candidate [N] is an available predictor candidate, andcalculating the number of available predictor candidates. The followingis a description of FIG. 40 .

In step S711, the motion vector predictor candidate calculation unit 711determines whether a prediction block candidate [N] is (1) decoded byintra prediction, (2) located outside a boundary of a slice or a picturewhich includes a current block to be decoded, or (3) not decoded yet.

Here, if the determination result in step S711 is true (Yes in S711),the motion vector predictor candidate calculation unit 711 sets theprediction block candidate [N] as a non-available predictor candidate instep S712. On the other hand, if the determination result in step S711is false (No in S711), the motion vector predictor candidate calculationunit 711 sets the prediction block candidate [N] as an availablepredictor candidate in step S713.

In step S714, the motion vector predictor candidate calculation unit 711determines whether the prediction block candidate [N] is an availablepredictor candidate or a co-located block candidate. Here, if thedetermination result in step S714 is true (Yes in S714), the motionvector predictor candidate calculation unit 711 adds 1 to the number ofavailable predictor candidates, and updates the value in step S5. On theother hand, if the determination result in step S714 is false (No inS714), the motion vector predictor candidate calculation unit 711 doesnot update the number of available predictor candidates.

As described above, if a prediction block candidate is a co-locatedblock, the motion vector predictor candidate calculation Unit 711 adds 1to the number of available predictor candidates, irrespective of whetherthe co-located block is an available predictor candidate or anon-available predictor candidate. Accordingly, even if information of aco-located block is lost due to packet loss or the like, there is nodifference in the number of available predictor candidates between themoving picture coding apparatus and the moving picture decodingapparatus.

The motion vector predictor candidate list size is set to the number ofavailable predictor candidates in step S702 in FIG. 39 . Furthermore, inS703 in FIG. 39 , the motion vector predictor candidate list size isused for variable-length decoding motion vector predictor indices.Accordingly, even if reference picture information including informationof a co-located block or the like is lost, the moving picture decodingapparatus 700 can successfully decode motion vector predictor indices.

FIG. 41 is a flowchart showing detailed processing of step S704 in FIG.39 . Specifically, FIG. 41 shows a method for calculating motion vectorpredictor candidates. The following is a description of FIG. 41 .

In step S721, the motion vector predictor candidate calculation unit 711derives a motion vector predictor candidate in the prediction directionX from the prediction block candidate [N] using Expressions 1 and 2above, and adds the derived candidate to a corresponding one of themotion vector predictor candidate lists.

In step S722, the motion vector predictor candidate calculation unit 711searches for and deletes a non-available predictor candidate and aredundant candidate from the motion vector predictor candidate lists, asshown in FIGS. 30 and 31 .

In step S723, the motion vector predictor candidate calculation unit 711adds a new candidate to a corresponding one of the motion vectorpredictor candidate lists, using the same method as in FIG. 34 .

FIG. 42 shows an example of syntax used when a motion vector predictorindex is added to a bitstream. In FIG. 42 , inter_pred_flag indicates aprediction direction flag, and mvp_idx indicates a motion vectorpredictor index. NumMVPCand indicates the motion vector predictorcandidate list size, and the size is set to the number of availablepredictor candidates calculated in the processing flow in FIG. 40 in thepresent embodiment.

As described above, according to the moving picture decoding apparatus700 according to the present embodiment, the motion vector predictorcandidate list size to be used when a motion vector predictor index iscoded or decoded can be calculated by using a method independent ofreference picture information including information of a co-locatedblock and the like. Accordingly, the moving picture decoding apparatus700 can appropriately decode a bitstream having improved errorresistance.

More specifically, the moving picture decoding apparatus 700 accordingto the present embodiment always adds 1 to the number of availablepredictor candidates if a prediction block candidate is a co-locatedblock, irrespective of whether the co-located block is an availablepredictor candidate. Then, the moving picture decoding apparatus 700determines bit strings to be assigned to motion vector predictor indicesusing the number of available predictor candidates calculated in thisway. Accordingly, even if reference picture information includinginformation of a co-located block is lost, the moving picture decodingapparatus 700 can successfully decode a motion vector predictor index.

Further, if the number of motion vector predictor candidates has notreached the number of available predictor candidates, the moving picturedecoding apparatus 700 according to the present embodiment canappropriately decode a bitstream for which coding efficiency has beenimproved by adding a new candidate having a new motion vector predictoras a motion vector predictor candidate.

It should be noted that in the present embodiment, although the movingpicture decoding apparatus 700 determines bit strings to be assigned tomotion vector predictor indices using the number of available predictorcandidates calculated by always adding 1 when a prediction blockcandidate is a co-located block, irrespective of whether the co-locatedblock is an available predictor candidate, the present invention is notlimited to this. For example, the moving picture decoding apparatus 700may determine bit strings to be assigned to motion vector predictorindices, using the number of available predictor candidates calculatedby also always adding 1 in the case of a prediction block candidateother than a co-located block in step S714 in FIG. 40 . Specifically,the moving picture decoding apparatus 700 may assign a bit string to amotion vector predictor index, using the motion vector predictorcandidate list size fixed to the maximum value N of the number of motionvector predictor candidates. In other words, assuming that allprediction block candidates are available predictor candidates, themoving picture decoding apparatus may fix the motion vector predictorcandidate list size to the maximum value N of the number of motionvector predictor candidates, and decode motion vector predictor indices.

For example, in the present embodiment, since the maximum value N of thenumber of motion vector predictor candidates is 5 (adjacent block A,adjacent block B, co-located block, adjacent block C, adjacent block D),the moving picture decoding apparatus 700 may always set the motionvector predictor candidate list size to 5, and decode motion vectorpredictor indices. Accordingly, the variable length decoding unit 701 ofthe moving picture decoding apparatus 700 can decode a motion vectorpredictor index in a bitstream, without referring to information ofadjacent blocks or a co-located block. As a result, for example,processing of steps S714 and S715 in FIG. 40 , for instance, can beskipped, and thus the amount of processing to be performed by thevariable length decoding unit 701 can be reduced.

FIG. 43 shows an example of syntax used when the motion vector predictorcandidate list size is fixed to the maximum value of the number ofmotion vector predictor candidates. As shown in FIG. 43 , NumMVPCand canbe deleted from the syntax if the motion vector predictor candidate listsize is fixed to the maximum value of the number of motion vectorpredictor candidates.

Embodiment 8

The present embodiment is a modification of the moving picture decodingapparatus according to Embodiment 7 above. The following is a specificdescription of a moving picture decoding apparatus according toEmbodiment 8.

FIG. 44 is a block diagram showing a configuration of a moving picturedecoding apparatus 800 according to Embodiment 8. The moving picturedecoding apparatus 800 decodes a coded image included in a bitstream ona block-by-block basis. Specifically, the moving picture decodingapparatus 800 decodes, on a block-by-block basis, a coded image includedin a bitstream generated by the moving picture coding apparatus 600according to Embodiment 6, for example. The moving picture decodingapparatus 800 includes a motion vector predictor candidate derivationunit 810, a decoding unit 820, and a prediction control unit 830.

The motion vector predictor candidate derivation unit 810 corresponds tothe motion vector predictor candidate calculation unit 711 in Embodiment7 above. The motion vector predictor candidate derivation unit 810derives motion vector predictor candidates. Then, the motion vectorpredictor candidate derivation unit 810 generates motion vectorpredictor candidate lists in which each derived motion vector predictorcandidate is associated with an index for identifying the motion vectorpredictor candidate (motion vector predictor index), for example.

As shown in FIG. 44 , the motion vector predictor candidate derivationunit 810 includes a maximum number determination unit 811, a firstderivation unit 812, an identification unit 813, a determination unit814, and a second derivation unit 815.

The maximum number determination unit 811 determines the maximum numberof motion vector predictor candidates. Specifically, the maximum numberdetermination unit 811 determines the maximum value N of the number ofprediction block candidates.

For example, the maximum number determination unit 811 may determine themaximum number of motion vector predictor candidates, using the samemethod as that used by the maximum number determination unit 611 inEmbodiment 6. Further, for example, the maximum number determinationunit 811 may determine the maximum number, based on informationindicating the maximum number added to a bitstream. Accordingly, themoving picture decoding apparatus 800 can decode an image coded bychanging the maximum number in a suitable unit.

It should be noted that here, although the maximum number determinationunit 811 is included in the motion vector predictor candidate derivationunit 810, the maximum number determination unit 811 may be included inthe decoding unit 820.

The first derivation unit 812 derives one or more first motion vectorpredictor candidate as with the first derivation unit 612 in Embodiment6. Specifically, the first derivation unit 812 derives each first motionvector predictor candidates, based on a motion vector used for decodinga block spatially or temporally adjacent to a current block to bedecoded. Then, for example, the first derivation unit 812 registers,into the motion vector predictor candidate lists, the one or more firstmotion vector predictor candidates derived in this way, each inassociation with a motion vector predictor index.

It should be noted that the first derivation unit 812 may derive, as thefirst motion vector predictor candidate, a motion vector used fordecoding a block which is spatially adjacent to a current block to bedecoded, and is not a non-available predictor candidate, for example.Accordingly, the first motion vector predictor candidate can be derivedfrom a block suitable for obtaining a motion vector predictor candidate.

The identification unit 813 identifies a first motion vector predictorcandidate (redundant candidate) having the same motion vector as that ofany other first motion vector predictor candidate, if a plurality of thefirst motion vector predictor candidates are derived. Then, theidentification unit 813 deletes the identified redundant candidate froma corresponding one of the motion vector predictor candidate lists.

The determination unit 814 determines whether the number of first motionvector predictor candidates is smaller than the determined maximumnumber. Here, the determination unit 814 determines whether the numberof first motion vector predictor candidates excluding the identifiedredundant first motion vector predictor candidate is smaller than thedetermined maximum number.

If it is determined that the number of first motion vector predictorcandidates is smaller than the determined maximum number, the secondderivation unit 815 derives one or more second motion vector predictorcandidates each having a predetermined vector as a motion vector.Specifically, the second derivation unit 815 derives the second motionvector predictor candidates such that the sum of the number of firstmotion vector predictor candidates and the number of second motionvector predictor candidates does not exceed the maximum number. Here,the second derivation unit 815 derives the second motion vectorpredictor candidates such that the sum of the number of first motionvector predictor candidates excluding a redundant candidate and thenumber of second motion vector predictor candidates does not exceed themaximum number.

The predetermined vector may be a zero vector as in Embodiment 3 above,for example. Accordingly, the second derivation unit 815 can derive amotion vector predictor candidate having a static area motion vector.Consequently, the moving picture decoding apparatus 800 canappropriately decode a bitstream for which coding efficiency has beenimproved. It should be noted that the predetermined vector does notnecessarily need to be a zero vector.

Then, the second derivation unit 815 registers, into the motion vectorpredictor candidate lists, the one or more second motion vectorpredictor candidates derived in this way, each in association with amotion vector predictor index, for example. At this time, the secondderivation unit 815 may register each second motion vector predictorcandidate into a corresponding one of the motion vector predictorcandidate lists, such that a motion vector predictor index having avalue smaller than that for the second motion vector predictorcandidates is assigned to each first motion vector predictor candidate.Consequently, the moving picture decoding apparatus 800 canappropriately decode a bitstream for which coding efficiency has beenimproved.

It should be noted that the second derivation unit 815 does notnecessarily need to derive the one or more second motion vectorpredictor candidates such that the sum of the number of first motionvector predictor candidates and the number of second motion vectorpredictor candidates will be the same as the determined maximum number.If the sum of the number of first motion vector predictor candidates andthe number of second motion vector predictor candidates is smaller thanthe determined maximum number, there may be a value of a motion vectorpredictor index which is not associated with a motion vector predictorcandidate, for example.

The decoding unit 820 decodes, using the determined maximum number, acoded index added to a bitstream and used for identifying a motionvector predictor candidate.

The prediction control unit 830 selects a motion vector predictor to beused for decoding a current block to be decoded, from among the one ormore first motion vector predictor candidates and the one or more secondmotion vector predictor candidates, based on the decoded index.Specifically, the prediction control unit 830 selects, from the motionvector predictor candidate lists, a motion vector predictor to be usedfor decoding a current block to be decoded.

Next is a description of various operations of the moving picturedecoding apparatus 800 constituted as described above.

FIG. 45 is a flowchart showing processing operation of the movingpicture decoding apparatus 800 according to Embodiment 8.

First, the maximum number determination unit 811 determines the maximumnumber of motion vector predictor candidates (S801). The firstderivation unit 812 derives one or more first motion vector predictorcandidates (S802). The identification unit 813 identifies a first motionvector predictor candidate (redundant candidate) having the same motionvector as that of any other first motion vector predictor candidate, ifa plurality of the first motion vector predictor candidates are derived(S803).

The determination unit 814 determines whether the number of first motionvector predictor candidates excluding a redundant candidate is smallerthan the determined maximum number (S804). Here, if it is determinedthat the number of first motion vector predictor candidates excluding aredundant candidate is smaller than the determined maximum number (Yesin S804), the second derivation unit 815 derives one or more secondmotion vector predictor candidates (S805). On the other hand, if it isnot determined that the number of first motion vector predictorcandidates excluding a redundant candidate is smaller than thedetermined maximum number (No in S804), the second derivation unit 815does not derive a second motion vector predictor candidate.

The decoding unit 820 decodes a coded index added to a bitstream andused for identifying a motion vector predictor candidate, using thedetermined maximum number (S806).

The prediction control unit 830 selects, from among the one or morefirst motion vector predictor candidates and the one or more secondmotion vector predictor candidates, a motion vector predictor to be usedfor decoding a current block to be decoded, based on the decoded index(S807).

It should be noted that here, although an index is decoded (S806) aftera motion vector predictor candidate is derived, the processing does notnecessarily need to be performed in such an order. For example,processing for deriving a motion vector predictor candidate (S802 toS805) may be performed after decoding an index (S806). Further, decodingan index (S806) and deriving a motion vector predictor candidate (S802to S805) may be performed in parallel. Accordingly, the decodingprocessing speed can be increased.

As described above, according to the moving picture decoding apparatus800 according to the present embodiment, the one or more second motionvector predictor candidates each having a predetermined vector as amotion vector can be derived. Therefore, the moving picture decodingapparatus 800 can derive, for example, a motion vector predictorcandidate having a static area motion vector or the like as the secondmotion vector predictor candidate. Specifically, the moving picturedecoding apparatus 800 can appropriately decode a bitstream in which ablock having predetermined motion is efficiently coded, andappropriately decode the bitstream for which coding efficiency has beenimproved.

Furthermore, according to the moving picture decoding apparatus 800according to the present embodiment, an index for identifying a motionvector predictor candidate can be decoded using the determined maximumnumber. Specifically, an index can be decoded without depending on thenumber of motion vector predictor candidates actually derived.Therefore, even if information (for example, information of a co-locatedblock and the like) necessary for deriving a motion vector predictorcandidate is lost, the moving picture decoding apparatus 800 can decodethe index, and thus error resistance can be improved. Furthermore, themoving picture decoding apparatus 800 can decode an index withoutwaiting for derivation of a motion vector predictor candidate, and thuscan also perform in parallel deriving a motion vector predictorcandidate and decoding an index.

Furthermore, according to the moving picture decoding apparatus 800according to the present embodiment, if it is determined that the numberof first motion vector predictor candidates is smaller than the maximumnumber, one or more second motion vector predictor candidates can bederived. Therefore, the moving picture decoding apparatus 800 canincrease the number of motion vector predictor candidates in a rangewhich does not exceed the maximum number, and appropriately decode abitstream for which coding efficiency has been improved.

Further, according to the moving picture decoding apparatus 800according to the present embodiment, one or more second motion vectorpredictor candidates can be derived according to the number of firstmotion vector predictor candidates excluding a redundant first motionvector predictor candidate. As a result, the moving picture decodingapparatus 800 can increase the number of second motion vector predictorcandidates, and increase the types of motion vectors selectable asmotion vector predictor candidates. Consequently, the moving picturedecoding apparatus 800 can appropriately decode a bitstream for whichcoding efficiency has been furthermore improved.

It should be noted that in the present embodiment, although the movingpicture decoding apparatus 800 includes the identification unit 813, themoving picture decoding apparatus 800 does not necessarily need toinclude the identification unit 813, as in Embodiment 6. Specifically,step S803 does not necessarily need to be included in the flowchartshown in FIG. 45 . Even in such a case, the moving picture decodingapparatus 800 can decode an index for identifying a motion vectorpredictor candidate using the determined maximum number, and thus canimprove error resistance.

Further, although in the present embodiment, the first derivation unit812 derives the first motion vector predictor candidates, and thereafterthe identification unit 813 identifies a redundant candidate as shown inFIG. 45 , the processing does not necessarily need to be performedsequentially in this way. For example, the first derivation unit 812 mayderive a motion vector predictor candidate having a motion vector thatis not the same as that of any first motion vector predictor candidatealready derived, as the first motion vector predictor candidate. Thisallows the first derivation unit 812 to exclude, from the first motionvector predictor candidates, a motion vector predictor candidate havingthe same motion vector as a motion vector of any of the first motionvector predictor candidates which have already been derived. As aresult, the moving picture decoding apparatus 800 can increase thenumber of second motion vector predictor candidates, and increase thetypes of motion vectors selectable as motion vector predictorcandidates. Consequently, the moving picture decoding apparatus 800 canappropriately decode a bitstream for which coding efficiency has beenfurthermore improved.

Although the above is a description of the moving picture codingapparatus and the moving picture decoding apparatus according to one ormore aspects of the present invention, based on the embodiments, thepresent invention is not limited to the above embodiments. The hereindisclosed subject matter is to be considered descriptive andillustrative only, and the appended Claims are of a scope intended tocover and encompass not only the particular embodiments disclosed, butalso equivalent structures, methods, and/or uses.

Each of the constituent elements in the above-described embodiments maybe configured in the form of an exclusive hardware product, or may berealized by executing a software program suitable for the structuralelement. Each of the constituent elements may be realized by means thata program executing unit such as a CPU and a processor reads andexecutes the software program recorded on a recording medium such as ahard disc or a semiconductor memory. Here, the software program forrealizing the moving picture coding apparatus or the moving picturedecoding apparatus according to the above embodiments is a programdescribed below.

Specifically, this program causes a computer to execute a moving picturecoding method for calculating a motion vector predictor to be used whencoding a motion vector of a current block to be coded, and coding thecurrent block, to generate a bitstream, the method including: derivingeach of one or more first motion vector predictor candidates, based on amotion vector used for coding a block spatially or temporally adjacentto the current block; deriving one or more second motion vectorpredictor candidates each having a predetermined vector as a motionvector; selecting, from among the one or more first motion vectorpredictor candidates and the one or more second motion vector predictorcandidates, the motion vector predictor to be used for coding the motionvector of the current block; and adding an index for identifying themotion vector predictor to the bitstream.

Alternatively, this program causes the computer to execute a movingpicture decoding method for calculating a motion vector predictor to beused when decoding a motion vector of a current block to be decodedwhich is included in a bitstream, and decoding the current block, themethod including: deriving each of one or more first motion vectorpredictor candidates, based on a motion vector used for decoding a blockspatially or temporally adjacent to the current block; deriving one ormore second motion vector predictor candidates each having apredetermined vector as a motion vector; obtaining an index foridentifying one of one or more motion vector predictor candidates fromthe bitstream; and selecting, based on the obtained index, the motionvector predictor to be used when decoding the current block, from amongthe one or more first motion vector predictor candidates and the one ormore second motion vector predictor candidates.

Embodiment 9

The processing described in each of embodiments can be simplyimplemented in an independent computer system, by recording, in arecording medium, a program for implementing the configurations of themoving picture coding method (image coding method) and the movingpicture decoding method (image decoding method) described in each ofembodiments. The recording media may be any recording media as long asthe program can be recorded, such as a magnetic disk, an optical disk, amagnetic optical disk, an IC card, and a semiconductor memory.

Hereinafter, the applications to the moving picture coding method (imagecoding method) and the moving picture decoding method (image decodingmethod) described in each of embodiments and systems using thereof willbe described. The system has a feature of having an image coding anddecoding apparatus that includes an image coding apparatus using theimage coding method and an image decoding apparatus using the imagedecoding method. Other configurations in the system can be changed asappropriate depending on the cases.

FIG. 46 illustrates an overall configuration of a content providingsystem ex100 for implementing content distribution services. The areafor providing communication services is divided into cells of desiredsize, and base stations ex106, ex107, ex108, ex109, and ex110 which arefixed wireless stations are placed in each of the cells.

The content providing system ex100 is connected to devices, such as acomputer ex111, a personal digital assistant (PDA) ex112, a cameraex113, a cellular phone ex114 and a game machine ex115, via the Internetex101, an Internet service provider ex102, a telephone network ex104, aswell as the base stations ex106 to ex110, respectively.

However, the configuration of the content providing system ex100 is notlimited to the configuration shown in FIG. 46 , and a combination inwhich any of the elements are connected is acceptable. In addition, eachdevice may be directly connected to the telephone network ex104, ratherthan via the base stations ex106 to ex110 which are the fixed wirelessstations. Furthermore, the devices may be interconnected to each othervia a short distance wireless communication and others.

The camera ex113, such as a digital video camera, is capable ofcapturing video. A camera ex116, such as a digital camera, is capable ofcapturing both still images and video. Furthermore, the cellular phoneex114 may be the one that meets any of the standards such as GlobalSystem for Mobile Communications (GSM) (registered trademark), CodeDivision Multiple Access (CDMA), Wideband-Code Division Multiple Access(W-CDMA), Long Term Evolution (LTE), and High Speed Packet Access(HSPA). Alternatively, the cellular phone ex114 may be a PersonalHandyphone System (PHS).

In the content providing system ex100, a streaming server ex103 isconnected to the camera ex113 and others via the telephone network ex104and the base station ex109, which enables distribution of images of alive show and others. In such a distribution, a content (for example,video of a music live show) captured by the user using the camera ex113is coded as described above in each of embodiments (i.e., the camerafunctions as the image coding apparatus according to an aspect of thepresent invention), and the coded content is transmitted to thestreaming server ex103. On the other hand, the streaming server ex103carries out stream distribution of the transmitted content data to theclients upon their requests. The clients include the computer ex111, thePDA ex112, the camera ex113, the cellular phone ex114, and the gamemachine ex115 that are capable of decoding the above-mentioned codeddata. Each of the devices that have received the distributed datadecodes and reproduces the coded data (i.e., functions as the imagedecoding apparatus according to an aspect of the present invention).

The captured data may be coded by the camera ex113 or the streamingserver ex103 that transmits the data, or the coding processes may beshared between the camera ex113 and the streaming server ex103.Similarly, the distributed data may be decoded by the clients or thestreaming server ex103, or the decoding processes may be shared betweenthe clients and the streaming server ex103. Furthermore, the data of thestill images and video captured by not only the camera ex113 but alsothe camera ex116 may be transmitted to the streaming server ex103through the computer ex111. The coding processes may be performed by thecamera ex116, the computer ex111, or the streaming server ex103, orshared among them.

Furthermore, the coding and decoding processes may be performed by anLSI ex500 generally included in each of the computer ex111 and thedevices. The LSI ex500 may be configured of a single chip or a pluralityof chips. Software for coding and decoding video may be integrated intosome type of a recording medium (such as a CD-ROM, a flexible disk, anda hard disk) that is readable by the computer ex111 and others, and thecoding and decoding processes may be performed using the software.Furthermore, when the cellular phone ex114 is equipped with a camera,the video data obtained by the camera may be transmitted. The video datais data coded by the LSI ex500 included in the cellular phone ex114.

Furthermore, the streaming server ex103 may be composed of servers andcomputers, and may decentralize data and process the decentralized data,record, or distribute data.

As described above, the clients may receive and reproduce the coded datain the content providing system ex100. In other words, the clients canreceive and decode information transmitted by the user, and reproducethe decoded data in real time in the content providing system ex100, sothat the user who does not have any particular right and equipment canimplement personal broadcasting.

Aside from the example of the content providing system ex100, at leastone of the moving picture coding apparatus (image coding apparatus) andthe moving picture decoding apparatus (image decoding apparatus)described in each of embodiments may be implemented in a digitalbroadcasting system ex200 illustrated in FIG. 47 . More specifically, abroadcast station ex201 communicates or transmits, via radio waves to abroadcast satellite ex202, multiplexed data obtained by multiplexingaudio data and others onto video data. The video data is data coded bythe moving picture coding method described in each of embodiments (i.e.,data coded by the image coding apparatus according to an aspect of thepresent invention). Upon receipt of the multiplexed data, the broadcastsatellite ex202 transmits radio waves for broadcasting. Then, a home-useantenna ex204 with a satellite broadcast reception function receives theradio waves. Next, a device such as a television (receiver) ex300 and aset top box (STB) ex217 decodes the received multiplexed data, andreproduces the decoded data (i.e., functions as the image decodingapparatus according to an aspect of the present invention).

Furthermore, a reader/recorder ex218 (i) reads and decodes themultiplexed data recorded on a recording medium ex215, such as a DVD anda BD, or (i) codes video signals in the recording medium ex215, and insome cases, writes data obtained by multiplexing an audio signal on thecoded data. The reader/recorder ex218 can include the moving picturedecoding apparatus or the moving picture coding apparatus as shown ineach of embodiments. In this case, the reproduced video signals aredisplayed on the monitor ex219, and can be reproduced by another deviceor system using the recording medium ex215 on which the multiplexed datais recorded. It is also possible to implement the moving picturedecoding apparatus in the set top box ex217 connected to the cable ex203for a cable television or to the antenna ex204 for satellite and/orterrestrial broadcasting, so as to display the video signals on themonitor ex219 of the television ex300. The moving picture decodingapparatus may be implemented not in the set top box but in thetelevision ex300.

FIG. 48 illustrates the television (receiver) ex300 that uses the movingpicture coding method and the moving picture decoding method describedin each of embodiments. The television ex300 includes: a tuner ex301that obtains or provides multiplexed data obtained by multiplexing audiodata onto video data, through the antenna ex204 or the cable ex203, etc.that receives a broadcast; a modulation/demodulation unit ex302 thatdemodulates the received multiplexed data or modulates data intomultiplexed data to be supplied outside; and amultiplexing/demultiplexing unit ex303 that demultiplexes the modulatedmultiplexed data into video data and audio data, or multiplexes videodata and audio data coded by a signal processing unit ex306 into data.

The television ex300 further includes: a signal processing unit ex306including an audio signal processing unit ex304 and a video signalprocessing unit ex305 that decode audio data and video data and codeaudio data and video data, respectively (which function as the imagecoding apparatus and the image decoding apparatus according to theaspects of the present invention); and an output unit ex309 including aspeaker ex307 that provides the decoded audio signal, and a display unitex308 that displays the decoded video signal, such as a display.Furthermore, the television ex300 includes an interface unit ex317including an operation input unit ex312 that receives an input of a useroperation. Furthermore, the television ex300 includes a control unitex310 that controls overall each constituent element of the televisionex300, and a power supply circuit unit ex311 that supplies power to eachof the elements. Other than the operation input unit ex312, theinterface unit ex317 may include: a bridge ex313 that is connected to anexternal device, such as the reader/recorder ex218; a slot unit ex314for enabling attachment of the recording medium ex216, such as an SDcard; a driver ex315 to be connected to an external recording medium,such as a hard disk; and a modem ex316 to be connected to a telephonenetwork. Here, the recording medium ex216 can electrically recordinformation using a non-volatile/volatile semiconductor memory elementfor storage. The constituent elements of the television ex300 areconnected to each other through a synchronous bus.

First, the configuration in which the television ex300 decodesmultiplexed data obtained from outside through the antenna ex204 andothers and reproduces the decoded data will be described. In thetelevision ex300, upon a user operation through a remote controllerex220 and others, the multiplexing/demultiplexing unit ex303demultiplexes the multiplexed data demodulated by themodulation/demodulation unit ex302, under control of the control unitex310 including a CPU. Furthermore, the audio signal processing unitex304 decodes the demultiplexed audio data, and the video signalprocessing unit ex305 decodes the demultiplexed video data, using thedecoding method described in each of embodiments, in the televisionex300. The output unit ex309 provides the decoded video signal and audiosignal outside, respectively. When the output unit ex309 provides thevideo signal and the audio signal, the signals may be temporarily storedin buffers ex318 and ex319, and others so that the signals arereproduced in synchronization with each other. Furthermore, thetelevision ex300 may read multiplexed data not through a broadcast andothers but from the recording media ex215 and ex216, such as a magneticdisk, an optical disk, and a SD card. Next, a configuration in which thetelevision ex300 codes an audio signal and a video signal, and transmitsthe data outside or writes the data on a recording medium will bedescribed. In the television ex300, upon a user operation through theremote controller ex220 and others, the audio signal processing unitex304 codes an audio signal, and the video signal processing unit ex305codes a video signal, under control of the control unit ex310 using thecoding method described in each of embodiments. Themultiplexing/demultiplexing unit ex303 multiplexes the coded videosignal and audio signal, and provides the resulting signal outside. Whenthe multiplexing/demultiplexing unit ex303 multiplexes the video signaland the audio signal, the signals may be temporarily stored in thebuffers ex320 and ex321, and others so that the signals are reproducedin synchronization with each other. Here, the buffers ex318, ex319,ex320, and ex321 may be plural as illustrated, or at least one buffermay be shared in the television ex300. Furthermore, data may be storedin a buffer so that the system overflow and underflow may be avoidedbetween the modulation/demodulation unit ex302 and themultiplexing/demultiplexing unit ex303, for example.

Furthermore, the television ex300 may include a configuration forreceiving an AV input from a microphone or a camera other than theconfiguration for obtaining audio and video data from a broadcast or arecording medium, and may code the obtained data. Although thetelevision ex300 can code, multiplex, and provide outside data in thedescription, it may be capable of only receiving, decoding, andproviding outside data but not the coding, multiplexing, and providingoutside data.

Furthermore, when the reader/recorder ex218 reads or writes multiplexeddata from or on a recording medium, one of the television ex300 and thereader/recorder ex218 may decode or code the multiplexed data, and thetelevision ex300 and the reader/recorder ex218 may share the decoding orcoding.

As an example, FIG. 49 illustrates a configuration of an informationreproducing/recording unit ex400 when data is read or written from or onan optical disk. The information reproducing/recording unit ex400includes constituent elements ex401, ex402, ex403, ex404, ex405, ex406,and ex407 to be described hereinafter. The optical head ex401 irradiatesa laser spot in a recording surface of the recording medium ex215 thatis an optical disk to write information, and detects reflected lightfrom the recording surface of the recording medium ex215 to read theinformation. The modulation recording unit ex402 electrically drives asemiconductor laser included in the optical head ex401, and modulatesthe laser light according to recorded data. The reproductiondemodulating unit ex403 amplifies a reproduction signal obtained byelectrically detecting the reflected light from the recording surfaceusing a photo detector included in the optical head ex401, anddemodulates the reproduction signal by separating a signal componentrecorded on the recording medium ex215 to reproduce the necessaryinformation. The buffer ex404 temporarily holds the information to berecorded on the recording medium ex215 and the information reproducedfrom the recording medium ex215. The disk motor ex405 rotates therecording medium ex215. The servo control unit ex406 moves the opticalhead ex401 to a predetermined information track while controlling therotation drive of the disk motor ex405 so as to follow the laser spot.The system control unit ex407 controls overall the informationreproducing/recording unit ex400. The reading and writing processes canbe implemented by the system control unit ex407 using variousinformation stored in the buffer ex404 and generating and adding newinformation as necessary, and by the modulation recording unit ex402,the reproduction demodulating unit ex403, and the servo control unitex406 that record and reproduce information through the optical headex401 while being operated in a coordinated manner. The system controlunit ex407 includes, for example, a microprocessor, and executesprocessing by causing a computer to execute a program for read andwrite.

Although the optical head ex401 irradiates a laser spot in thedescription, it may perform high-density recording using near fieldlight.

FIG. 50 illustrates the recording medium ex215 that is the optical disk.On the recording surface of the recording medium ex215, guide groovesare spirally formed, and an information track ex230 records, in advance,address information indicating an absolute position on the diskaccording to change in a shape of the guide grooves. The addressinformation includes information for determining positions of recordingblocks ex231 that are a unit for recording data. Reproducing theinformation track ex230 and reading the address information in anapparatus that records and reproduces data can lead to determination ofthe positions of the recording blocks. Furthermore, the recording mediumex215 includes a data recording area ex233, an inner circumference areaex232, and an outer circumference area ex234. The data recording areaex233 is an area for use in recording the user data. The innercircumference area ex232 and the outer circumference area ex234 that areinside and outside of the data recording area ex233, respectively arefor specific use except for recording the user data. The informationreproducing/recording unit 400 reads and writes coded audio, coded videodata, or multiplexed data obtained by multiplexing the coded audio andvideo data, from and on the data recording area ex233 of the recordingmedium ex215.

Although an optical disk having a layer, such as a DVD and a BD isdescribed as an example in the description, the optical disk is notlimited to such, and may be an optical disk having a multilayerstructure and capable of being recorded on a part other than thesurface. Furthermore, the optical disk may have a structure formultidimensional recording/reproduction, such as recording ofinformation using light of colors with different wavelengths in the sameportion of the optical disk and for recording information havingdifferent layers from various angles.

Furthermore, a car ex210 having an antenna ex205 can receive data fromthe satellite ex202 and others, and reproduce video on a display devicesuch as a car navigation system ex211 set in the car ex210, in thedigital broadcasting system ex200. Here, a configuration of the carnavigation system ex211 will be a configuration, for example, includinga GPS receiving unit from the configuration illustrated in FIG. 48 . Thesame will be true for the configuration of the computer ex111, thecellular phone ex114, and others.

FIG. 51A illustrates the cellular phone ex114 that uses the movingpicture coding method and the moving picture decoding method describedin embodiments. The cellular phone ex114 includes: an antenna ex350 fortransmitting and receiving radio waves through the base station ex110; acamera unit ex365 capable of capturing moving and still images; and adisplay unit ex358 such as a liquid crystal display for displaying thedata such as decoded video captured by the camera unit ex365 or receivedby the antenna ex350. The cellular phone ex114 further includes: a mainbody unit including an operation key unit ex366; an audio output unitex357 such as a speaker for output of audio; an audio input unit ex356such as a microphone for input of audio; a memory unit ex367 for storingcaptured video or still pictures, recorded audio, coded or decoded dataof the received video, the still pictures, e-mails, or others; and aslot unit ex364 that is an interface unit for a recording medium thatstores data in the same manner as the memory unit ex367.

Next, an example of a configuration of the cellular phone ex114 will bedescribed with reference to FIG. 51B. In the cellular phone ex114, amain control unit ex360 designed to control overall each unit of themain body including the display unit ex358 as well as the operation keyunit ex366 is connected mutually, via a synchronous bus ex370, to apower supply circuit unit ex361, an operation input control unit ex362,a video signal processing unit ex355, a camera interface unit ex363, aliquid crystal display (LCD) control unit ex359, amodulation/demodulation unit ex352, a multiplexing/demultiplexing unitex353, an audio signal processing unit ex354, the slot unit ex364, andthe memory unit ex367.

When a call-end key or a power key is turned ON by a user's operation,the power supply circuit unit ex361 supplies the respective units withpower from a battery pack so as to activate the cell phone ex114.

In the cellular phone ex114, the audio signal processing unit ex354converts the audio signals collected by the audio input unit ex356 invoice conversation mode into digital audio signals under the control ofthe main control unit ex360 including a CPU, ROM, and RAM. Then, themodulation/demodulation unit ex352 performs spread spectrum processingon the digital audio signals, and the transmitting and receiving unitex351 performs digital-to-analog conversion and frequency conversion onthe data, so as to transmit the resulting data via the antenna ex350.Also, in the cellular phone ex114, the transmitting and receiving unitex351 amplifies the data received by the antenna ex350 in voiceconversation mode and performs frequency conversion and theanalog-to-digital conversion on the data. Then, themodulation/demodulation unit ex352 performs inverse spread spectrumprocessing on the data, and the audio signal processing unit ex354converts it into analog audio signals, so as to output them via theaudio output unit ex357.

Furthermore, when an e-mail in data communication mode is transmitted,text data of the e-mail inputted by operating the operation key unitex366 and others of the main body is sent out to the main control unitex360 via the operation input control unit ex362. The main control unitex360 causes the modulation/demodulation unit ex352 to perform spreadspectrum processing on the text data, and the transmitting and receivingunit ex351 performs the digital-to-analog conversion and the frequencyconversion on the resulting data to transmit the data to the basestation ex110 via the antenna ex350. When an e-mail is received,processing that is approximately inverse to the processing fortransmitting an e-mail is performed on the received data, and theresulting data is provided to the display unit ex358.

When video, still images, or video and audio in data communication modeis or are transmitted, the video signal processing unit ex355 compressesand codes video signals supplied from the camera unit ex365 using themoving picture coding method shown in each of embodiments (i.e.,functions as the image coding apparatus according to the aspect of thepresent invention), and transmits the coded video data to themultiplexing/demultiplexing unit ex353. In contrast, during when thecamera unit ex365 captures video, still images, and others, the audiosignal processing unit ex354 codes audio signals collected by the audioinput unit ex356, and transmits the coded audio data to themultiplexing/demultiplexing unit ex353.

The multiplexing/demultiplexing unit ex353 multiplexes the coded videodata supplied from the video signal processing unit ex355 and the codedaudio data supplied from the audio signal processing unit ex354, using apredetermined method. Then, the modulation/demodulation unit(modulation/demodulation circuit unit) ex352 performs spread spectrumprocessing on the multiplexed data, and the transmitting and receivingunit ex351 performs digital-to-analog conversion and frequencyconversion on the data so as to transmit the resulting data via theantenna ex350.

When receiving data of a video file which is linked to a Web page andothers in data communication mode or when receiving an e-mail with videoand/or audio attached, in order to decode the multiplexed data receivedvia the antenna ex350, the multiplexing/demultiplexing unit ex353demultiplexes the multiplexed data into a video data bitstream and anaudio data bitstream, and supplies the video signal processing unitex355 with the coded video data and the audio signal processing unitex354 with the coded audio data, through the synchronous bus ex370. Thevideo signal processing unit ex355 decodes the video signal using amoving picture decoding method corresponding to the moving picturecoding method shown in each of embodiments (i.e., functions as the imagedecoding apparatus according to the aspect of the present invention),and then the display unit ex358 displays, for instance, the video andstill images included in the video file linked to the Web page via theLCD control unit ex359. Furthermore, the audio signal processing unitex354 decodes the audio signal, and the audio output unit ex357 providesthe audio.

Furthermore, similarly to the television ex300, a terminal such as thecellular phone ex114 probably have 3 types of implementationconfigurations including not only (i) a transmitting and receivingterminal including both a coding apparatus and a decoding apparatus, butalso (ii) a transmitting terminal including only a coding apparatus and(iii) a receiving terminal including only a decoding apparatus. Althoughthe digital broadcasting system ex200 receives and transmits themultiplexed data obtained by multiplexing audio data onto video data inthe description, the multiplexed data may be data obtained bymultiplexing not audio data but character data related to video ontovideo data, and may be not multiplexed data but video data itself.

As such, the moving picture coding method and the moving picturedecoding method in each of embodiments can be used in any of the devicesand systems described. Thus, the advantages described in each ofembodiments can be obtained.

Furthermore, the present invention is not limited to embodiments, andvarious modifications and revisions are possible without departing fromthe scope of the present invention.

Embodiment 10

Video data can be generated by switching, as necessary, between (i) themoving picture coding method or the moving picture coding apparatusshown in each of embodiments and (ii) a moving picture coding method ora moving picture coding apparatus in conformity with a differentstandard, such as MPEG-2, MPEG-4 AVC, and VC-1.

Here, when a plurality of video data that conforms to the differentstandards is generated and is then decoded, the decoding methods need tobe selected to conform to the different standards. However, since towhich standard each of the plurality of the video data to be decodedconform cannot be detected, there is a problem that an appropriatedecoding method cannot be selected.

In order to solve the problem, multiplexed data obtained by multiplexingaudio data and others onto video data has a structure includingidentification information indicating to which standard the video dataconforms. The specific structure of the multiplexed data including thevideo data generated in the moving picture coding method and by themoving picture coding apparatus shown in each of embodiments will behereinafter described. The multiplexed data is a digital stream in theMPEG-2 Transport Stream format.

FIG. 52 illustrates a structure of the multiplexed data. As illustratedin FIG. 52 , the multiplexed data can be obtained by multiplexing atleast one of a video stream, an audio stream, a presentation graphicsstream (PG), and an interactive graphics stream. The video streamrepresents primary video and secondary video of a movie, the audiostream (IG) represents a primary audio part and a secondary audio partto be mixed with the primary audio part, and the presentation graphicsstream represents subtitles of the movie. Here, the primary video isnormal video to be displayed on a screen, and the secondary video isvideo to be displayed on a smaller window in the primary video.Furthermore, the interactive graphics stream represents an interactivescreen to be generated by arranging the GUI components on a screen. Thevideo stream is coded in the moving picture coding method or by themoving picture coding apparatus shown in each of embodiments, or in amoving picture coding method or by a moving picture coding apparatus inconformity with a conventional standard, such as MPEG-2, MPEG-4 AVC, andVC-1. The audio stream is coded in accordance with a standard, such asDolby-AC-3, Dolby Digital Plus, MLP, DTS, DTS-HD, and linear PCM.

Each stream included in the multiplexed data is identified by PID. Forexample, 0x1011 is allocated to the video stream to be used for video ofa movie, 0x1100 to 0x111F are allocated to the audio streams, 0x1200 to0x121F are allocated to the presentation graphics streams, 0x1400 to0x141F are allocated to the interactive graphics streams, 0x1B00 to0x1B1F are allocated to the video streams to be used for secondary videoof the movie, and 0x1A00 to 0x1A1F are allocated to the audio streams tobe used for the secondary audio to be mixed with the primary audio.

FIG. 53 schematically illustrates how data is multiplexed. First, avideo stream ex235 composed of video frames and an audio stream ex238composed of audio frames are transformed into a stream of PES packetsex236 and a stream of PES packets ex239, and further into TS packetsex237 and TS packets ex240, respectively. Similarly, data of apresentation graphics stream ex241 and data of an interactive graphicsstream ex244 are transformed into a stream of PES packets ex242 and astream of PES packets ex245, and further into TS packets ex243 and TSpackets ex246, respectively. These TS packets are multiplexed into astream to obtain multiplexed data ex247.

FIG. 54 illustrates how a video stream is stored in a stream of PESpackets in more detail. The first bar in FIG. 54 shows a video framestream in a video stream. The second bar shows the stream of PESpackets. As indicated by arrows denoted as yy1, yy2, yy3, and yy4 inFIG. 54 , the video stream is divided into pictures as I pictures, Bpictures, and P pictures each of which is a video presentation unit, andthe pictures are stored in a payload of each of the PES packets. Each ofthe PES packets has a PES header, and the PES header stores aPresentation Time-Stamp (PTS) indicating a display time of the picture,and a Decoding Time-Stamp (DTS) indicating a decoding time of thepicture.

FIG. 55 illustrates a format of TS packets to be finally written on themultiplexed data. Each of the TS packets is a 188-byte fixed lengthpacket including a 4-byte TS header having information, such as a PIDfor identifying a stream and a 184-byte TS payload for storing data. ThePES packets are divided, and stored in the TS payloads, respectively.When a BD ROM is used, each of the TS packets is given a 4-byteTP_Extra_Header, thus resulting in 192-byte source packets. The sourcepackets are written on the multiplexed data. The TP_Extra_Header storesinformation such as an Arrival_Time_Stamp (ATS). The ATS shows atransfer start time at which each of the TS packets is to be transferredto a PID filter. The source packets are arranged in the multiplexed dataas shown at the bottom of FIG. 55 . The numbers incrementing from thehead of the multiplexed data are called source packet numbers (SPNs).

Each of the TS packets included in the multiplexed data includes notonly streams of audio, video, subtitles and others, but also a ProgramAssociation Table (PAT), a Program Map Table (PMT), and a Program ClockReference (PCR). The PAT shows what a PID in a PMT used in themultiplexed data indicates, and a PID of the PAT itself is registered aszero. The PMT stores PIDs of the streams of video, audio, subtitles andothers included in the multiplexed data, and attribute information ofthe streams corresponding to the PIDs. The PMT also has variousdescriptors relating to the multiplexed data. The descriptors haveinformation such as copy control information showing whether copying ofthe multiplexed data is permitted or not. The PCR stores STC timeinformation corresponding to an ATS showing when the PCR packet istransferred to a decoder, in order to achieve synchronization between anArrival Time Clock (ATC) that is a time axis of ATSs, and an System TimeClock (STC) that is a time axis of PTSs and DTSs.

FIG. 56 illustrates the data structure of the PMT in detail. A PMTheader is disposed at the top of the PMT. The PMT header describes thelength of data included in the PMT and others. A plurality ofdescriptors relating to the multiplexed data is disposed after the PMTheader. Information such as the copy control information is described inthe descriptors. After the descriptors, a plurality of pieces of streaminformation relating to the streams included in the multiplexed data isdisposed. Each piece of stream information includes stream descriptorseach describing information, such as a stream type for identifying acompression codec of a stream, a stream PID, and stream attributeinformation (such as a frame rate or an aspect ratio). The streamdescriptors are equal in number to the number of streams in themultiplexed data.

When the multiplexed data is recorded on a recording medium and others,it is recorded together with multiplexed data information files.

Each of the multiplexed data information files is management informationof the multiplexed data as shown in FIG. 57 . The multiplexed datainformation files are in one to one correspondence with the multiplexeddata, and each of the files includes multiplexed data information,stream attribute information, and an entry map.

As illustrated in FIG. 57 , the multiplexed data information includes asystem rate, a reproduction start time, and a reproduction end time. Thesystem rate indicates the maximum transfer rate at which a system targetdecoder to be described later transfers the multiplexed data to a PIDfilter. The intervals of the ATSs included in the multiplexed data areset to not higher than a system rate. The reproduction start timeindicates a PTS in a video frame at the head of the multiplexed data. Aninterval of one frame is added to a PTS in a video frame at the end ofthe multiplexed data, and the PTS is set to the reproduction end time.

As shown in FIG. 58 , a piece of attribute information is registered inthe stream attribute information, for each PID of each stream includedin the multiplexed data. Each piece of attribute information hasdifferent information depending on whether the corresponding stream is avideo stream, an audio stream, a presentation graphics stream, or aninteractive graphics stream. Each piece of video stream attributeinformation carries information including what kind of compression codecis used for compressing the video stream, and the resolution, aspectratio and frame rate of the pieces of picture data that is included inthe video stream. Each piece of audio stream attribute informationcarries information including what kind of compression codec is used forcompressing the audio stream, how many channels are included in theaudio stream, which language the audio stream supports, and how high thesampling frequency is. The video stream attribute information and theaudio stream attribute information are used for initialization of adecoder before the player plays back the information.

In the present embodiment, the multiplexed data to be used is of astream type included in the PMT. Furthermore, when the multiplexed datais recorded on a recording medium, the video stream attributeinformation included in the multiplexed data information is used. Morespecifically, the moving picture coding method or the moving picturecoding apparatus described in each of embodiments includes a step or aunit for allocating unique information indicating video data generatedby the moving picture coding method or the moving picture codingapparatus in each of embodiments, to the stream type included in the PMTor the video stream attribute information. With the configuration, thevideo data generated by the moving picture coding method or the movingpicture coding apparatus described in each of embodiments can bedistinguished from video data that conforms to another standard.

Furthermore, FIG. 59 illustrates steps of the moving picture decodingmethod according to the present embodiment. In Step exS100, the streamtype included in the PMT or the video stream attribute informationincluded in the multiplexed data information is obtained from themultiplexed data. Next, in Step exS101, it is determined whether or notthe stream type or the video stream attribute information indicates thatthe multiplexed data is generated by the moving picture coding method orthe moving picture coding apparatus in each of embodiments. When it isdetermined that the stream type or the video stream attributeinformation indicates that the multiplexed data is generated by themoving picture coding method or the moving picture coding apparatus ineach of embodiments, in Step exS102, decoding is performed by the movingpicture decoding method in each of embodiments. Furthermore, when thestream type or the video stream attribute information indicatesconformance to the conventional standards, such as MPEG-2, MPEG-4 AVC,and VC-1, in Step exS103, decoding is performed by a moving picturedecoding method in conformity with the conventional standards.

As such, allocating a new unique value to the stream type or the videostream attribute information enables determination whether or not themoving picture decoding method or the moving picture decoding apparatusthat is described in each of embodiments can perform decoding. Even whenmultiplexed data that conforms to a different standard is input, anappropriate decoding method or apparatus can be selected. Thus, itbecomes possible to decode information without any error. Furthermore,the moving picture coding method or apparatus, or the moving picturedecoding method or apparatus in the present embodiment can be used inthe devices and systems described above.

Embodiment 11

Each of the moving picture coding method, the moving picture codingapparatus, the moving picture decoding method, and the moving picturedecoding apparatus in each of embodiments is typically achieved in theform of an integrated circuit or a Large Scale Integrated (LSI) circuit.As an example of the LSI, FIG. 60 illustrates a configuration of the LSIex500 that is made into one chip. The LSI ex500 includes elements ex501,ex502, ex503, ex504, ex505, ex506, ex507, ex508, and ex509 to bedescribed below, and the elements are connected to each other through abus ex510. The power supply circuit unit ex505 is activated by supplyingeach of the elements with power when the power supply circuit unit ex505is turned on.

For example, when coding is performed, the LSI ex500 receives an AVsignal from a microphone ex117, a camera ex113, and others through an AVIO ex509 under control of a control unit ex501 including a CPU ex502, amemory controller ex503, a stream controller ex504, and a drivingfrequency control unit ex512. The received AV signal is temporarilystored in an external memory ex511, such as an SDRAM. Under control ofthe control unit ex501, the stored data is segmented into data portionsaccording to the processing amount and speed to be transmitted to asignal processing unit ex507. Then, the signal processing unit ex507codes an audio signal and/or a video signal. Here, the coding of thevideo signal is the coding described in each of embodiments.Furthermore, the signal processing unit ex507 sometimes multiplexes thecoded audio data and the coded video data, and a stream IO ex506provides the multiplexed data outside. The provided multiplexed data istransmitted to the base station ex107, or written on the recordingmedium ex215. When data sets are multiplexed, the data should betemporarily stored in the buffer ex508 so that the data sets aresynchronized with each other.

Although the memory ex511 is an element outside the LSI ex500, it may beincluded in the LSI ex500. The buffer ex508 is not limited to onebuffer, but may be composed of buffers. Furthermore, the LSI ex500 maybe made into one chip or a plurality of chips.

Furthermore, although the control unit ex501 includes the CPU ex502, thememory controller ex503, the stream controller ex504, the drivingfrequency control unit ex512, the configuration of the control unitex501 is not limited to such. For example, the signal processing unitex507 may further include a CPU. Inclusion of another CPU in the signalprocessing unit ex507 can improve the processing speed. Furthermore, asanother example, the CPU ex502 may serve as or be a part of the signalprocessing unit ex507, and, for example, may include an audio signalprocessing unit. In such a case, the control unit ex501 includes thesignal processing unit ex507 or the CPU ex502 including a part of thesignal processing unit ex507.

The name used here is LSI, but it may also be called IC, system LSI,super LSI, or ultra LSI depending on the degree of integration.

Moreover, ways to achieve integration are not limited to the LSI, and aspecial circuit or a general purpose processor and so forth can alsoachieve the integration. Field Programmable Gate Array (FPGA) that canbe programmed after manufacturing LSIs or a reconfigurable processorthat allows re-configuration of the connection or configuration of anLSI can be used for the same purpose.

In the future, with advancement in semiconductor technology, a brand-newtechnology may replace LSI. The functional blocks can be integratedusing such a technology. The possibility is that the present inventionis applied to biotechnology.

Embodiment 12

When video data generated in the moving picture coding method or by themoving picture coding apparatus described in each of embodiments isdecoded, compared to when video data that conforms to a conventionalstandard, such as MPEG-2, MPEG-4 AVC, and VC-1 is decoded, theprocessing amount probably increases. Thus, the LSI ex500 needs to beset to a driving frequency higher than that of the CPU ex502 to be usedwhen video data in conformity with the conventional standard is decoded.However, when the driving frequency is set higher, there is a problemthat the power consumption increases.

In order to solve the problem, the moving picture decoding apparatus,such as the television ex300 and the LSI ex500 is configured todetermine to which standard the video data conforms, and switch betweenthe driving frequencies according to the determined standard. FIG. 61illustrates a configuration ex800 in the present embodiment. A drivingfrequency switching unit ex803 sets a driving frequency to a higherdriving frequency when video data is generated by the moving picturecoding method or the moving picture coding apparatus described in eachof embodiments. Then, the driving frequency switching unit ex803instructs a decoding processing unit ex801 that executes the movingpicture decoding method described in each of embodiments to decode thevideo data. When the video data conforms to the conventional standard,the driving frequency switching unit ex803 sets a driving frequency to alower driving frequency than that of the video data generated by themoving picture coding method or the moving picture coding apparatusdescribed in each of embodiments. Then, the driving frequency switchingunit ex803 instructs the decoding processing unit ex802 that conforms tothe conventional standard to decode the video data.

More specifically, the driving frequency switching unit ex803 includesthe CPU ex502 and the driving frequency control unit ex512 in FIG. 60 .Here, each of the decoding processing unit ex801 that executes themoving picture decoding method described in each of embodiments and thedecoding processing unit ex802 that conforms to the conventionalstandard corresponds to the signal processing unit ex507 in FIG. 60 .The CPU ex502 determines to which standard the video data conforms.Then, the driving frequency control unit ex512 determines a drivingfrequency based on a signal from the CPU ex502. Furthermore, the signalprocessing unit ex507 decodes the video data based on the signal fromthe CPU ex502. For example, the identification information described inEmbodiment 10 is probably used for identifying the video data. Theidentification information is not limited to the one described inEmbodiment 10 but may be any information as long as the informationindicates to which standard the video data conforms. For example, whenwhich standard video data conforms to can be determined based on anexternal signal for determining that the video data is used for atelevision or a disk, etc., the determination may be made based on suchan external signal. Furthermore, the CPU ex502 selects a drivingfrequency based on, for example, a look-up table in which the standardsof the video data are associated with the driving frequencies as shownin FIG. 63 . The driving frequency can be selected by storing thelook-up table in the buffer ex508 and in an internal memory of an LSI,and with reference to the look-up table by the CPU ex502.

FIG. 62 illustrates steps for executing a method in the presentembodiment. First, in Step exS200, the signal processing unit ex507obtains identification information from the multiplexed data. Next, inStep exS201, the CPU ex502 determines whether or not the video data isgenerated by the coding method and the coding apparatus described ineach of embodiments, based on the identification information. When thevideo data is generated by the moving picture coding method and themoving picture coding apparatus described in each of embodiments, inStep exS202, the CPU ex502 transmits a signal for setting the drivingfrequency to a higher driving frequency to the driving frequency controlunit ex512. Then, the driving frequency control unit ex512 sets thedriving frequency to the higher driving frequency. On the other hand,when the identification information indicates that the video dataconforms to the conventional standard, such as MPEG-2, MPEG-4 AVC, andVC-1, in Step exS203, the CPU ex502 transmits a signal for setting thedriving frequency to a lower driving frequency to the driving frequencycontrol unit ex512. Then, the driving frequency control unit ex512 setsthe driving frequency to the lower driving frequency than that in thecase where the video data is generated by the moving picture codingmethod and the moving picture coding apparatus described in each ofembodiment.

Furthermore, along with the switching of the driving frequencies, thepower conservation effect can be improved by changing the voltage to beapplied to the LSI ex500 or an apparatus including the LSI ex500. Forexample, when the driving frequency is set lower, the voltage to beapplied to the LSI ex500 or the apparatus including the LSI ex500 isprobably set to a voltage lower than that in the case where the drivingfrequency is set higher.

Furthermore, when the processing amount for decoding is larger, thedriving frequency may be set higher, and when the processing amount fordecoding is smaller, the driving frequency may be set lower as themethod for setting the driving frequency. Thus, the setting method isnot limited to the ones described above. For example, when theprocessing amount for decoding video data in conformity with MPEG-4 AVCis larger than the processing amount for decoding video data generatedby the moving picture coding method and the moving picture codingapparatus described in each of embodiments, the driving frequency isprobably set in reverse order to the setting described above.

Furthermore, the method for setting the driving frequency is not limitedto the method for setting the driving frequency lower. For example, whenthe identification information indicates that the video data isgenerated by the moving picture coding method and the moving picturecoding apparatus described in each of embodiments, the voltage to beapplied to the LSI ex500 or the apparatus including the LSI ex500 isprobably set higher. When the identification information indicates thatthe video data conforms to the conventional standard, such as MPEG-2,MPEG-4 AVC, and VC-1, the voltage to be applied to the LSI ex500 or theapparatus including the LSI ex500 is probably set lower. As anotherexample, when the identification information indicates that the videodata is generated by the moving picture coding method and the movingpicture coding apparatus described in each of embodiments, the drivingof the CPU ex502 does not probably have to be suspended. When theidentification information indicates that the video data conforms to theconventional standard, such as MPEG-2, MPEG-4 AVC, and VC-1, the drivingof the CPU ex502 is probably suspended at a given time because the CPUex502 has extra processing capacity. Even when the identificationinformation indicates that the video data is generated by the movingpicture coding method and the moving picture coding apparatus describedin each of embodiments, in the case where the CPU ex502 has extraprocessing capacity, the driving of the CPU ex502 is probably suspendedat a given time. In such a case, the suspending time is probably setshorter than that in the case where when the identification informationindicates that the video data conforms to the conventional standard,such as MPEG-2, MPEG-4 AVC, and VC-1.

Accordingly, the power conservation effect can be improved by switchingbetween the driving frequencies in accordance with the standard to whichthe video data conforms. Furthermore, when the LSI ex500 or theapparatus including the LSI ex500 is driven using a battery, the batterylife can be extended with the power conservation effect.

Embodiment 13

There are cases where a plurality of video data that conforms todifferent standards, is provided to the devices and systems, such as atelevision and a cellular phone. In order to enable decoding theplurality of video data that conforms to the different standards, thesignal processing unit ex507 of the LSI ex500 needs to conform to thedifferent standards. However, the problems of increase in the scale ofthe circuit of the LSI ex500 and increase in the cost arise with theindividual use of the signal processing units ex507 that conform to therespective standards.

In order to solve the problem, what is conceived is a configuration inwhich the decoding processing unit for implementing the moving picturedecoding method described in each of embodiments and the decodingprocessing unit that conforms to the conventional standard, such asMPEG-2, MPEG-4 AVC, and VC-1 are partly shared. Ex900 in FIG. 64A showsan example of the configuration. For example, the moving picturedecoding method described in each of embodiments and the moving picturedecoding method that conforms to MPEG-4 AVC have, partly in common, thedetails of processing, such as entropy coding, inverse quantization,deblocking filtering, and motion compensated prediction. The details ofprocessing to be shared probably include use of a decoding processingunit ex902 that conforms to MPEG-4 AVC. In contrast, a dedicateddecoding processing unit ex901 is probably used for other processingunique to an aspect of the present invention. Since the aspect of thepresent invention is characterized by motion compensation in particular,for example, the dedicated decoding processing unit ex901 is used formotion compensation. Otherwise, the decoding processing unit is probablyshared for one of the entropy decoding, deblocking filtering, andinverse quantization, or all of the processing. The decoding processingunit for implementing the moving picture decoding method described ineach of embodiments may be shared for the processing to be shared, and adedicated decoding processing unit may be used for processing unique tothat of MPEG-4 AVC.

Furthermore, ex1000 in FIG. 64B shows another example in that processingis partly shared. This example uses a configuration including adedicated decoding processing unit ex1001 that supports the processingunique to an aspect of the present invention, a dedicated decodingprocessing unit ex1002 that supports the processing unique to anotherconventional standard, and a decoding processing unit ex1003 thatsupports processing to be shared between the moving picture decodingmethod according to the aspect of the present invention and theconventional moving picture decoding method. Here, the dedicateddecoding processing units ex1001 and ex1002 are not necessarilyspecialized for the processing according to the aspect of the presentinvention and the processing of the conventional standard, respectively,and may be the ones capable of implementing general processing.Furthermore, the configuration of the present embodiment can beimplemented by the LSI ex500.

As such, reducing the scale of the circuit of an LSI and reducing thecost are possible by sharing the decoding processing unit for theprocessing to be shared between the moving picture decoding methodaccording to the aspect of the present invention and the moving picturedecoding method in conformity with the conventional standard.

INDUSTRIAL APPLICABILITY

A moving picture coding method and a moving picture decoding methodaccording to the present invention are applicable to any multimediadata, can improve coding efficiency, and are useful as a moving picturecoding method and a moving picture decoding method in storage,transmission, communication, and the like using cellular phones, DVDapparatuses, and personal computers, for example.

What is claimed is:
 1. A moving picture coding apparatus for coding acurrent block, the moving picture coding apparatus comprising: aprocessor; and a non-transitory memory, wherein the processor performs,using the non-transitory memory, processes including: deriving a firstcandidate from a first motion vector that has been used to code a firstblock; determining whether a total number of one or more candidatesincluding the first candidate is less than a maximum candidate number;deriving a second candidate having a second motion vector after derivingthe first candidate when the total number of the one or more candidatesincluding the first candidate is less than the maximum candidate number,the second motion vector including a zero vector; selecting a candidatefrom a plurality of candidates, the plurality of candidates includingthe first candidate and the second candidate; and coding the currentblock using the selected candidate.
 2. A moving picture coding methodfor coding a current block, the moving picture coding method comprising:deriving a first candidate from a first motion vector that has been usedto code a first block; determining whether a total number of one or morecandidates including the first candidate is less than a maximumcandidate number; deriving a second candidate having a second motionvector after deriving the first candidate when the total number of theone or more candidates including the first candidate is less than themaximum candidate number, the second motion vector including a zerovector; selecting a candidate from a plurality of candidates, theplurality of candidates including the first candidate and the secondcandidate; and coding, by at least one of a processor or a circuit, thecurrent block using the selected candidate.
 3. A non-transitorycomputer-readable medium including a program for coding a current block,the program, when executed by a processor, causing the processor toperform processes, the processes comprising: deriving a first candidatefrom a first motion vector that has been used to code a first block;determining whether a total number of one or more candidates includingthe first candidate is less than a maximum candidate number; deriving asecond candidate having a second motion vector after deriving the firstcandidate when the total number of the one or more candidates includingthe first candidate is less than the maximum candidate number, thesecond motion vector including a zero vector; selecting a candidate froma plurality of candidates, the plurality of candidates including thefirst candidate and the second candidate; and coding the current blockusing the selected candidate.